Topotactic reversible phase transition between room-temperature and a new low-temperature modification in the MCl3(THF)3 system

Both single crystals of VCl₃(THF)₃ as well as isotypic cocrystals of the composition MCl₃(THF)₃, M=Ti/V 1/3, undergo a topotactic reversible phase transition to a hitherto unknown low-temperature modification. The close relationship between this new structure and the room-temperature phase determined by Cottonet al. is discussed from the molecular and the intermolecular point of view: Both modifications are built up by conformationally very similar molecules which change their arrangement during the phase transition. Lattice energy calculations confirm that these two alternative arrangements correspond to minima of almost the same packing energy.Dedicated to Professor Dr. G. E. Herberich on the occasion of his 60th birthday.     

K~+-FREE INDUCED EARLY AFTERDEPOL-ARIZATION IN CARDIAC VENTRICULAR FIBERS OF GUINEA PIG AFTER COLD TREATMENT

The genesis and elimination of early afterdepolarizations (EADs) have been investigated in guinea pig cardiac ventricular fibers after a short period of cooling (5h, 2—4℃). After rewarming them to 37℃, EADs could be induced by K~+-free superfusion at an appropriate driving stimulation (0.2 Hz) in all preparations. A high level plateau, which linearly increases its duration with time, appears ahead of EADs. The critical point of the plateau occurred steadily at the level of -47±4 mV. Two types of triggered activity, all of which are the rhythmic activities in low level of membrane potential (-50 to -60 mV), appear on the platcau. There is no significant change after overdriving. Agonists of the Na-K pump (K~+ and Tl~+) could stop the rhythmic activity immediately and turn the low level of membrane potential to high one. The results showed that high level plateau is the basis of genesis of EADs, and the activation of Na-K pump plays an important part in stopping triggered rhythms arising from EADs.     

量子态选择的分子离子解离动力学：阈值光电子-光离子符合成像技术的应用

阈值光电子一光离子符合速度成像技术通过对光电子和符合的光离子同时进行速度聚焦控制,大幅提高了电子和离子的收集效率和离子平动能分辨率,成为开展气相分子光电离和光电离．解离动力学研究的有效工具．利用该技术,我们精确地测量了分子的电离能、离子出现势等重要参数,并且开展了若干具有量子态或内能选择的离子解离动力学研究,描绘了相关势能面存在浅势阱等重要动力学特征,讨论了不同振动态和电子态的激发对解离机理和产物通道的重要影响．     

血清HCG、孕酮联合检测在早期先兆流产治疗中的价值分析

目的通过研究探讨血清β-HCG、孕酮联合检测在早期先兆流产治疗中的临床价值。方法随机选取广东省中山市东升镇东升医院2015年1月—2016年9月期间收治的100例早期先兆流产患者作为研究对象,并按随机数字分组法将所有入选患者分为观察组与对照组(各50例),观察组给予血清β-HCG、孕酮联合检测,对照组仅给予血清孕酮检测,分析比较两组患者检验的有效率。结果观察组经联合检测后血清β-HCG、孕酮水平较仅给予血清孕酮检测对照组的水平低(P0.05);观察组经血清β-HCG、孕酮联合检测后临床检验有效率显著优于仅给予血清孕酮检测的对照组,其临床检验的敏感度、阴性预测值及诊断准确率均显著优于仅给予血清孕酮检测的对照组(P0.05)。结论血清β-HCG、孕酮联合检测具有较高的诊断准确率,在早期先兆流产诊断中更具有指导意义,有利于临床根据血清β-HCG、孕酮检测值采取有效治疗措施。     

Metabolic characterization of the early stage of hepatic fibrosis in rat using GC‐TOF/MS and multivariate data analyses

The aim of this study was to explore the changes in the urine metabolic spectrum in rats with the early stage of liver fibrosis using gas chromatography–time of flight/mass spectrometry (GC‐TOF/MS), try to search for potential biomarkers and elucidate the probably metabonomic pathogenesis. The early stage of liver fibrosis was established with a single subcutaneous injection of carbon tetrachloride twice each week for 4 weeks continuously. At the end of the experiment, GC‐TOF/MS technology with multivariate statistical approaches such as principal component analysis, partial least squares‐discriminant analysis and orthogonal partial least squares‐discriminant analysis was used to analyze the changes in the metabolic spectrum trajectory and identify potential biomarkers. Twelve potential biomarkers in the model group, such as succinic acid, threonine and lactose, were selected, which indicate that the metabonomic pathogenesis of the early stage of liver fibrosis may be related to disorders of energy metabolism, amino acid metabolism and fatty acid metabolism.     

Reaction of early transition metal complexes with macrocycles. II. Synthesis and structure of TiCl3(H2O) · 18-crown-6, a compound with a unique bidentate bonding mode for the 18-crown-6 molecule

18-crown-6 reacts with TiCl₃ in CH₂Cl₂ to form a complex in which the crown ether functions as a tridentate ligand. Addition of moist hexane affords a molecular complex in which the crown ether functions as a bidentate ligand. A water molecule is bonded directly to the titanium atom and is further hydrogen bonded to three of the oxygen atoms of the crown. The deep blue crystals of the CH₂Cl₂ adduct belong to the monoclinic space groupP2₁/n witha=13.481(8),b=8.021(5),c=21.425(9) Å, =97.32(5)°, and _calc = 1.51 g cm^–3 forZ=4. Refinement led to a conventionalR value of 0.040 based on 873 observed reflections. The Ti–O bond distances for the crown oxygen atoms are 2.123(8) and 2.154(9) Å, while the oxygen atom of the water molecule is bonded at 2.072(8) Å. The octahedral coordination sphere of the titanium atom is completed by the three chlorine atoms at distances of 2.340(5), 2.352(4), and 2.373(4) Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82034 (10 pages).     

Quantitative surface analysis by Auger and x-ray photoelectron spectroscopy

Recent developments in quantitative surface analysis by Auger (AES) and x-ray photoelectron (XPS) spectroscopies are reviewed and problems relating to a more accurate quantitative interpretation of AES/XPS experimental data are discussed. Special attention is paid to consideration of elementary physical processes involved and influence of multiple scattering effects on signal line intensities. In particular, the major features of core-shell ionization by electron impact, Auger transitions and photoionization are considered qualitatively and rigorous approaches used to calculate the respective transition probabilities are analysed. It is shown that, in amorphous and polycrystalline targets, incoherent scattering of primary and signal Auger and photoelectrons can be described by solving analytically a kinetic equation with appropriate boundary conditions. The analytical results for the angular and energy distribution, the mean escape depth, and the escape probability as a function of depth of origin of signal electrons as well as that for the backscattering factor in AES are in good agreement with the corresponding Mote Carlo simulation data. Methods for inelastic background subtraction, surface composition determination and depth-profile reconstructions by angle-resolved AES/XPS are discussed. Examples of novel techniques based on x-ray induced photoemission are considered.     

一氧化二氮的光电离质谱研究

在入射电子能量2500eV、能量分辨200meV的条件下测量了一氧化二氮分子在7.8～24.5 eV的光学振子强度密度谱和光电离质谱,报道了N2O+、NO+、O+、N2+和N+等离子在较高能量分辨下的部分光学振子强度密度,首次给出了一氧化二氮分子在13.0～21.0 eV能区中性解离的振子强度密度.并在对这些数据进行分析的基础上阐述了一氧化二氮分子超激发态的不同退激发道的竞争过程.     

Coincidences of projections and linear n-valued maps of tori

We prove that the Nielsen fixed point number N(φ) of an n-valued map φ:X?X of a compact connected triangulated orientable q-manifold without boundary is equal to the Nielsen coincidence number of the projections of the graph of φ, a subset of X×X, to the two factors. For certain q×q integer matrices A, there exist “linear” n-valued maps Φn,A,σ:Tq?Tq of q-tori that generalize the single-valued maps fA:Tq→Tq induced by the linear transformations TA:Rq→Rq defined by TA(v)=Av. By calculating the Nielsen coincidence number of the projections of its graph, we calculate N(Φn,A,σ) for a large class of linear n-valued maps.     

时间测度上一类种群动力系统的周期解

在时间测度上研究一类具有时滞和Beddington-DeAngelis功能性反应的n种群食物链系统.利用Mawhin重合度理论建立了这一类系统的正周期解存在的充分性条件,从而使这一类系统的连续时间和离散时间情形即微分方程和差分方程得到了统一研究.