求解完全强非线性自治系统周期解及其稳定性的三变量迭代法

本文提出用广义位移x,基波幅值变化率da/dt=A(a)和系统频率ω(a)进行迭代的一种解析方法——三变量迭代法,求解一般的二阶完全强非线性自治系统的周期解及其稳定性。通过若干实例计算,表明了该方法行之有效。     

Synthesis,Characterization and Thermal Behaviors of 4-Amino-5-nitro-1,2,3-triazole(ANTZ)and Its Derivatives

4‐Amino‐5‐nitro‐1,2,3‐triazole (ANTZ) and its derivatives, such as 2‐(4‐amino‐5‐nitro‐1,2,3‐trazole‐1‐yl)‐1,3,5‐trinitrobenzene (T‐ANTZ) and 4‐amino‐5‐nitro‐1,2,3‐triazole (M‐ANTZ), were synthesized and characterized, whose structures were confirmed by IR, NMR and elemental analysis. The thermal behaviors of ANTZ, T‐ANTZ and M‐ANTZ were studied by the methods of DSC and TG‐DTG, and the results showed that there is an obvious melting process of ANTZ with melting point of 278.38°C, while there is no melting process in the thermal behavior of T‐ANTZ and M‐ANTZ (the derivatives of ATNZ).     

Xylocarpanoids A and B, unique C28 skeleton limonoids from Xylocarpus granatum

One novel tetranortriterpenoid derivative, xylocarponoid A, representing the first example of C28 skeleton limonoid, was isolated from the seeds of the Chinese mangrove, Xylocarpus granatum. Its C-1′-epimer, xylocarponoid B, was formed in CDCl₃. Their structures were elucidated by extensive spectroscopic analysis. A plausible biosynthetic pathway of xylocarponoid A was proposed.     

A 3D Metal‐organic Framework Containing [Cd(3‐CPOA)]n (3‐CPOA2– = 3‐Carboxyphenoxyacetato Dianion) Expanded by 4,4′‐Bipyridine

The hydrothermal reaction of Cd(NO₃) · 4H₂O with 4,4′‐bipyridine (bipy) and 3‐carboxyphenoxyacetatic acid (3‐H₂CPOA) afforded a 3D metal‐organic framework (MOF) [Cd(3‐CPOA)(bipy)]_n · 3.5nH₂O, which was characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and X‐ray diffraction. The single‐crystal structural analysis revealed that it has a Cds‐type topological network with 1D channels that contain encapsulated water molecular tapes.     

Solvothermal synthesis of well-defined TiO(2) mesoporous nanotubes with enhanced photocatalytic activity

High efficiency TiO(2) photocatalyst in porous nanotubes were prepared by solvothermal alcoholysis of TiOSO(4) in the presence of carbon nanotube template.     

Mapping of phosphorylation sites in human MSK1 activated by a novel interaction with MRK‐β

The desire to map reliable phosphorylation signaling network has motivated the development of high‐performance techniques. Targeted biochemical studies and updated methods employing MS techniques are most used in mapping the phosphorylation sites and verifying novel interactions of kinases. Previously, we have established a novel method to efficiently facilitate more comprehensive, accurate phosphorylation site mapping of individual phosphoproteins by using combination of multiple stage MS analysis with target‐decoy database search against the much smaller targeted database. In this study, by applying this method, we have identified the phosphorylation sites in human MSK1 mitogen‐ and stress‐activated protein kinase 1), which has been proved to be a multi‐phosphorylated kinase that plays key roles in various cell functions, activated by a novel interaction with MRK‐β. The results show that this method can find out not only those previously identified active sites in MSK1, but also some novel phosphorylated sites, which correlates with biochemical evidence that, besides p38 and extracellular signal‐regulated kinase, MRK‐β could also activate MSK1 through direct interaction. Hence, we conclude this method is sensitive and reliable as expected and it can be further combined with automated screening and biochemical study in efficiently building up a more comprehensive phosphoprotein network.     

Fragmentation investigation of brassinosteroid compounds by ion trap and quadrupole time-of-flight mass spectrometry

The fragmentation mechanisms of three types of brassinosteroids (BRs), 23,24‐tris‐epicastasterone, epicastasterone, tris–epicastasterone, 24‐epibrassinolide and 6‐deoxo‐24‐epicastasterone, have been extensively investigated by tandem mass spectrometry (MSⁿ, n = 1, 2, 3, 4, 5) with the assistance of high mass accuracy quadrupole time‐of‐flight mass spectrometry (QToF MS). The electrospray ionization (ESI) mass spectrometric fragmentation pathways of these five BRs were comprehensively elucidated for the first time. Cleavages of side chains, neutral losses of water or other molecules and opening of a ring induce the main fragmentation patterns. The results from the present study can potentially afford important guidance for the structural elucidation of different BRs and provide some fundamental data for metabolomic analysis of BRs. Copyright © 2010 John Wiley & Sons, Ltd.     

胶束电动毛细管色谱-电喷雾质谱联用法同时测定妇宁栓中的5种有效成分

应用胶束电动毛细管色谱-电喷雾电离质谱联用法同时测定了妇宁栓中的小檗碱、巴马汀、苦参碱、儿茶素和黄芩苷5种主要有效成分的含量。在未涂层石英毛细管柱(80 cm×50 μm)中,以40 mmol/L月桂酸-100 mmol/L氨水溶液(含25%的乙腈,pH 9.5)为缓冲液,分离电压为25.0 kV,各组分在16 min内得到完全分离。电喷雾质谱检测时采用50%异丙醇水溶液(含3 mmol/L乙酸)为鞘液。结果表明,小檗碱、巴马汀、苦参碱、儿茶素、黄芩苷的线性范围分别为0.03～15、0.05～15、0.2～250、1.5～300和2.0～500 mg/L,检出限分别为0.01、0.02、0.05、0.5、0.6 mg/L。5种组分的加标回收率为94.0%～104.0%,相对标准偏差(RSD)在0.3%～3.2%之间。该法简便、快速、准确,重现性好,可用于妇宁栓中小檗碱、巴马汀、苦参碱、儿茶素、黄芩苷含量的同时测定。     

Photophysical property of rhodamine-cored poly(amidoamine) dendrimers: Simultaneous effect of spirolactam ring-opening and PET process on sensing trivalent chromium ion

Two novel poly(amidoamine) (PAMAM) dendrimers, comprising rhodamine B unit in the core and 1-phenyl-3-methyl-5-pyrazolone unit at the periphery, have been synthesized and characterized. Both dendrimers displayed high selectivity and sensitivity towards Cr³⁺ ion. As considering the potential of being applied as fluorescent sensors for Cr³⁺ ion, we studied the complexes formed between the dendrimers and Cr³⁺ ion. Different PAMAM dendrimers had different recognition mechanism towards Cr³⁺ ion. For dendrimer G2, the recognition of Cr³⁺ was mainly due to the ring-opening of spirolactam. However, it significantly depended on the simultaneous effect of ring-opening of spirolactam and photoinduced electron transfer (PET) in the case of dendrimer G3.     

Improved charge trapping flash device with Al2O3/HfSiO stack as blocking layer

In this paper, we investigate an Al₂O₃/HfSiO stack as the blocking layer of a metal-oxide-nitride-oxide-silicon-type (MONOS) memory capacitor. Compared with a memory capacitor with a single HfSiO layer as the blocking layer or an Al₂O₃/HfO₂ stack as the blocking layer, the sample with the Al₂O₃/HfSiO stack as the blocking layer shows high program/erase (P/E) speed and good data retention characteristics. These improved performances can be explained by energy band engineering. The experimental results demonstrate that the memory device with an Al₂O₃/HfSiO stack as the blocking layer has great potential for further high-performance nonvolatile memory applications.