树按Balaban指标的排序(英文)

连通图G的Balaban指标(也称J指标)定义为J=J(G)=(|E(G)|)/μ+1∑_(uυ∈E(G)),其中σ_G(u)=∑(w∈V(G)d_G(u,w)此处μ是基圈数.Balaban指标常用于各种QSAR和QSPR的研究.本文根据Balaban指标的计算公式及文中提到的变换方式,我们得到了一些序关系.基于这些序关系,我们确定了n个顶点的树中具有最小Balaban指标的前21个树.     

1-（4-硝基苯）-3-（2-吡嗪）-三氮烯的合成及与锌（Ⅱ）的显色反应

报道了1-（4-硝基苯）-3-（2-吡嗪）-三氮烯（NPPT）的合成及与锌（Ⅱ）的显色反应。在非离子表面活性剂TritonX-100存在下,于pH8.8的KCl,H3BO3-NaOH缓冲介质中,NPPT与锌（Ⅱ）形成4∶1的黄棕色络合物,在465nm处有一最大吸收,表观摩尔吸光系数为3.15×104L·mol-1.cm-1,10mL溶液中,锌（Ⅱ）量在0—0.56μg范围内符合比尔定律。方法用于葡萄糖酸锌口服溶液中微量锌的测定,测定结果与AAS法相符。     

Permanence and global attractivity of a discrete Schoener’s competition model with delays

A discrete Schoener’s competitive model with delays is studied. Sufficient conditions which guarantee the permanence of the model and the global attractivity of positive solutions of the model are obtained. Numerical simulations show the feasibility of the main results.     

活性红2的微波辅助芬顿脱色处理 ——一个开放综合实验的设计

设计了一个开放综合实验.实验利用微波辅助芬顿对染料活性红2进行降解脱色处理,并对降解前后的紫外光谱、红外光谱、化学需氧量进行测定.实验涉及仪器分析、染料化学、环境工程等领域的知识与操作,有助于中、高年级学生对所学知识的融会贯通,从而提升学生的创新意识和能力.     

Critical review of bio/nano sensors for arsenic detection

Detection of arsenic is a long-standing challenge in environmental analytical chemistry. In recent years, using biomolecules and nanomaterials for sensing arsenic has been growingly reported. In this article, this field is critically reviewed based on some recent fundamental understandings including interactions between arsenic and gold, thiol, and DNA aptamers. First, taking advantage of the adsorption of As(III) on noble metal surfaces such as silver and gold, sensors were developed based on surface enhanced Raman spectroscopy, electrochemistry and colorimetry. In addition, by functionalizing metal nanoparticles with thiol containing molecules, As(III) induced aggregation of the particles based on As(III)/thiol interactions. As(V) interacts with metal oxides strongly and competitive sensors were developed by displacing pre-adsorbed DNA oligonucleotides. A DNA aptamer was selected for As(III) and many sensors were reported based on this aptamer, although careful binding measurements indicated that the sequence has no affinity towards As(III). Overall, bio/nano systems are promising for the detection of arsenic. Future work on fundamental studies, searching for more specific arsenic binding materials and aptamers, incorporation of sensors into portable devices, and more systematic test of sensors in real samples could be interesting and useful research topics.     

日落黄与牛血清白蛋白相互作用的电化学研究

利用微分脉冲伏安法,研究了日落黄与牛血清白蛋白之间的相互作用.试验结果表明,日落黄与牛血清白蛋白之间形成近似1:1的复合物,从而造成日落黄峰电流的降低,两者之间的结合主要依靠静电力,且结合常数随温度升高而降低.研究有利于从分子水平上了解日落黄和牛血清白蛋白之间的结合作用,为更进一步了解日落黄的生物代谢机理提供一定的理论参考.     

Recent developments in electrochemical detection of cadmium

Heavy metal cadmium (Cd) poses extreme toxicity to the environmental and human health, thus its detection provides a great challenge in the environmental and analytical science, yet the solution is needed urgently owing to the adverse effects. During the past years, the electrochemical techniques have received considerable attentions for Cd²⁺ determination due to their unique advantages. In this review, a common introduction was provided firstly and followed by the detection principles. Then, a fully comprehensive elucidation of the recent developments in electrochemical detection of Cd²⁺ was presented. Finally, the critical challenge and perspectives of Cd²⁺ detection were outlined.     

Switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

Without the need of any other additional filtering device, a triple-wavelength switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber is newly proposed and experimentally demonstrated. Three potential lasing wavelengths at about 2.0 nm interval with the side mode suppression ratio higher than 40 dB can be switched mainly by adjusting a polarization controller next to the few-mode high birefringence fiber in the Sagnac loop. In addition to the stable single-line lasing operation, simultaneous dual- and triple-line oscillations are also highly stable at room temperature with suppressing the intrinsic homogeneous gain broadening of the erbium-doped fiber.     

On hypersurfaces with two distinct principal curvatures in a unit sphere

We investigate the immersed hypersurfaces in a unit sphere . By using Otsuki's idea, we obtain the local and global classification results for immersed hypersurfaces in of constant m-th mean curvature and two distinct principal curvatures of multiplicities n−1,1 (in the local version, we assume that the principal curvatures are non-zero when m2). As the result, we prove that any local hypersurface in of constant mean curvature and two distinct principal curvatures is an open part of a complete hypersurface of the same curvature properties. The corresponding result does not hold for m-th mean curvature when m2.