基于样本均值的最优无重叠k-序对排序集抽样

本文提出了无重叠κ-序对排序集抽样方法,即在每个排序集中对κ-序对个体进行观测,并且不同的排序集的κ-序对之间没有任何重复.我们首先探究了此抽样方法得到的样本均值的有效性随每个排序集中κ-序对个体间的相关性变化的趋势.κ-序对个体间的相关性越强,样本均值的有效性损失越大.本文的目的是找到无重叠κ-序对排序集抽样方法中κ-序对分配的最优方案从而使样本均值的有效性损失最小,并证明了最优的无重叠κ-序对排序集抽样比广义排序集抽样以及简单随机抽样更有效.尽管无重叠κ-序对排序集抽样方法的统计效率低于经典的排序集抽样,但是在成本模型下,最优的无重叠κ-序对排序集抽样方法可以比经典的排序集抽样更有效.     

Global Solutions to a Nonlocal Fisher-KPP Type Problem

We consider a nonlocal Fisher-KPP reaction-diffusion model arising from population dynamics, consisting of a certain type reaction term \(u^{\alpha} ( 1-\int_{\varOmega}u^{\beta}dx ) \), where \(\varOmega\) is a bounded domain in \(\mathbb{R}^{n}(n \ge1)\). The energy method is applied to prove the global existence of the solutions and the results show that the long time behavior of solutions heavily depends on the choice of \(\alpha\), \(\beta\). More precisely, for \(1 \le\alpha <1+ ( 1-2/p ) \beta\), where \(p\) is the exponent from the Sobolev inequality, the problem has a unique global solution. Particularly, in the case of \(n \ge3\) and \(\beta=1\), \(\alpha<1+2/n\) is the known Fujita exponent (Fujita in J. Fac. Sci., Univ. Tokyo, Sect. 1A, Math. 13:109–124, 1966). Comparing to Fujita equation (Fujita in J. Fac. Sci., Univ. Tokyo, Sect. 1A, Math. 13:109–124, 1966), this paper will give an opposite result to our nonlocal problem.     

Two Zinc(II) and Nickel(II)‐based Complexes: Anti Breast Cancer Activity

Two zinc(II) and nickel(II) based coordination polymers, {[Zn(bibp)(MoO₄)](H₂O)₂}_n ( 1 ) [bibp = 4,4′‐bis(imidazol‐1‐yl)‐biphenyl] and [Ni₂(CN)₄(phen)₂]_n ( 2 ) (phen = 1,10‐phenanthroline), were synthesized and structurally characterized under solvothermal conditions. Compound 1 can be viewed as the connection of the 1D W‐type chain [Zn(trans‐bibp)] with the MoO₄^2– anion to form a uninodal 4‐connected net, whereas 2 features one‐dimensional Ni^II cyanide chains decorated either with linear Ni(CN)₄ side chains or with 1,10‐phenanthroline ligands bound directly to the Ni^II sites of the parent chain. In addition, in vitro anticancer activities of compounds 1 and 2 on four human breast cancer cells (MDA‐MB‐231, MDA‐MB‐468, SK‐BR‐3, and MCF7) was further determined.     

Rhodium/Chiral Diene‐Catalyzed Asymmetric 1,4‐Addition of Arylboronic Acids to Chromones: A Highly Enantioselective Pathway for Accessing Chiral Flavanones

Chromone has been noted to be one of the most challenging substrates in the asymmetric 1,4‐addition of α,β‐unsaturated carbonyl compounds. By employing the rhodium complex associated with a chiral diene ligand, (R,R)‐Ph‐bod*, the 1,4‐addition of a variety of arylboronic acids was realized to give high yields of the corresponding flavanones with excellent enantioselectivities (≥97 % ee, 99 % ee for most substrates). Ring‐opening side products, which would lead to erosion of product enantioselectivity, were not observed under the stated reaction conditions.     

Confinement crystallization of poly(l-lactide) induced by multiwalled carbon nanotubes and graphene nanosheets

Journal of Thermal Analysis and Calorimetry - Two sets of multiwalled carbon nanotubes (MWCNTs)/PLLA nanocomposites and graphene nanosheets (GNSs)/PLLA nanocomposites with various MWCNTs and GNSs...     

介孔碳材料CMK-3的合成及其吸附性能研究——介绍一个综合化学实验

介绍一个集物理化学、分析化学和无机化学为一体的综合实验——介孔碳材料CMK-3的合成及其吸附性能研究。实验通过合成具有高比表面积的介孔碳材料CMK-3,运用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和氮气吸附/脱附技术表征材料的形貌和多孔结构;考察了介孔碳材料CMK-3对水溶液中次甲基蓝染料分子的吸附性能。     

Synthesis of novel PEG-modified nitroimidazole derivatives via “hot-click” reaction and their biological evaluation as potential PET imaging agent for tumors

Ten novel PEG-modified nitroimidazole derivatives labeled with ¹⁸F were synthesized via “hot-click” reaction and evaluated as PET tumor tracers. The radiolabeling method was convenient and efficient, all compounds displayed high radiochemical purity (>95%), high yield (30–50%) and good stability in saline and human serum. The biodistribution studies in EMT-6 tumor-bearing mice demonstrated their tumor uptake values at 60 min postinjection were 1.46–2.99%ID/g, which were lower than [¹⁸F]FMISO (5.43%ID/g), their tumor-to-liver ratios were 0.73–1.07, higher than [¹⁸F]FMISO (0.69). In vitro MCF-7 cell uptake studies showed their uptake values have no significant difference between hypoxic and aerobic cells.     

Pseudospectral method with symplectic algorithm for the solution of time-dependent SchrSdinger equations

A pseudospectral method with symplectic algorithm for the solution of time-dependent Schrodinger equations （TDSE） is introduced. The spatial part of the wavefunction is discretized into sparse grid by pseudospectral method and the time evolution is given in symplectic scheme. This method allows us to obtain a highly accurate and stable solution of TDSE. The effectiveness and efficiency of this method is demonstrated by the high-order harmonic spectra of one-dimensional atom in strong laser field as compared with previously published work. The influence of the additional static electric field is also investigated.     

In vitro continuous amperometric monitoring of 5-hydroxytryptamine release from enterochromaffin cells of the guinea pig ileum

A diamond microelectrode was used to sensitively, reproducibly and stably record overflow of 5-hydroxytryptamine (5-HT, serotonin) from enterochromaffin cells (EC) of the intenstinal mucosal layer. 5-HT is an important neurotransmitter and paracrine signalling molecule in the gastrointestinal tract. The diamond microelectrode was formed by overcoating a sharpened 76 microm diameter Pt wire with a thin layer of conducting diamond. After insulation with polypropylene, the conically-shaped microelectrode had a diameter of about 10 microm at the tip and 80 microm at the cylindrical portion. The exposed length was 100-200 microm. Continuous amperometry with the microelectrode poised at a detection potential of 700 mV vs. Ag|AgCl was used to measure 5-HT overflow as an oxidation current. 5-HT overflow was elicited by both mechanical and electrical stimulation. Some minor electrode fouling, a common problem with the oxidative detection of 5-HT, was seen for diamond but the response stabilized enabling recording in vitro. Both 5-HT and the paracrine hormone, melatonin, were detected in the extracellular solution. The 5-HT oxidation current increased in the presence of the serotonin transporter (SERT) inhibitor, fluoxetine (1 microM), providing evidence that the oxidation current was associated with 5-HT.