Structural,electronic, and optical properties of doubly ortho‐linked quinoxaline/diphenylfluorene hybrids

The optical and electronic properties of spiro‐fluorene‐dibenzosuberene[d](1,4‐bis(4‐t‐butylphenyl)quinoxaline) 1a , spiro‐fluorene‐dibenzosuberene[d](1,4‐bis(4‐methoxyphenyl)quinoxaline) 1b , spiro‐fluorene‐dibenzosuberene[d](1‐(4‐(N,N‐diphenylamino)‐phenyl)‐quinoxaline) 1c , spiro‐fluorene‐dibenzosuberene[d](1,4‐bis(methylphenylamino)quinoxaline) 1d , spiro‐fluorene‐dibenzosuberene[d](1,4‐bis(methyl‐(4‐methylphenyl)amino)quinoxaline) 1e , spiro‐fluorene‐dibenzosuberene[d](1,4‐bis(methyl‐(4‐methoxyphenyl)amino)quinoxaline) 1f , 5,8‐bis‐(4‐methoxy‐phenyl)‐2,3‐diphenyl‐quinoxaline 1 , and N,N,N',N'‐tetraphenyl‐ 5h‐dibenzo[a,d]cycloheptene‐3,7‐diamine 2 were investigated theoretically in this paper. The doubly ortho‐linked quinoxaline/diphenylfluorene hybrids 1a – 1f show great potential as bipolar materials for the design of optimized organic light‐emitting diodes (OLEDs). Density functional theory (DFT) and ab initio HF were employed to study the geometric and electronic structures of these molecules in the ground state, and ab initio CIS were used to investigate the lowest singlet excited states. The radiative lifetime (τ) and the maximal absorption/emission wavelength of these molecules were calculated within time‐dependent DFT (TDDFT). The results show that the LUMO energies of the bipolar molecules 1a – 1d are all lower than those of 1 and 2 , consequently, the electron‐accepting abilities of 1a – 1d are greatly improved. The HOMO energies of 1c – 1f are all higher than those of 1 and 2 , suggesting that the hole‐creating abilities of 1c – 1f become better. Also, the results reveal that the HOMO and LUMO energies, energy gaps, IP, EA, as well as the maximal absorption/emission spectra can be tuned feasibly by changing the C5‐ and C8‐substituents in the quinoxaline backbone of these molecules. As expected, these materials show different emission spectra varying from 436.11 to 715.47 nm. Copyright © 2010 John Wiley & Sons, Ltd.     

On the analysis of a simple evolutionary algorithm on quadratic pseudo-boolean functions

Evolutionary algorithms are randomized search heuristics, which are often used as function optimizers. In this paper the well-known (1+1) Evolutionary Algorithm ((1+1) EA) and its multistart variants are studied. Several results on the expected runtime of the (1+1) EA on linear or unimodal functions have already been presented by other authors. This paper is focused on quadratic pseudo-boolean functions, i.e., polynomials of degree 2, a class of functions containing NP-hard optimization problems. Subclasses of the class of all quadratic functions are identified where the (1+1) EA is efficient, for other subclasses the (1+1) EA has exponential expected runtime, but a large enough success probability within polynomial time such that a multistart variant of the (1+1) EA is efficient. Finally, a particular quadratic function is identified where the EA and its multistart variants fail in polynomial time with overwhelming probability.     

An adaptive decision maker for constrained evolutionary optimization

An adaptive decision maker (ADM) is proposed for constrained evolutionary optimization. This decision maker, which is designed in the form of an adaptive penalty function, is used to decide which solution candidate prevails in the Pareto optimal set and to choose the individuals to be replaced. By integrating the ADM with a model of a population-based algorithm-generator, a novel generic constrained optimization evolutionary algorithm is derived. The performance of the new method is evaluated by 13 well-known benchmark test functions. It is shown that the ADM has powerful ability to balance the objective function and the constraint violations, and the results obtained are very competitive to other state-of-the-art techniques referred to in this paper in terms of the quality of the resulting solutions.     

三苯基膦和三甲基氯硅烷直接引发丙烯酸乙酯基团转移聚合的核磁共振动力学研究

用FT-NMR的动态³¹P NMR谱及动态¹H NMR谱对用三苯膦(TPP)和三甲基氯硅烷(TMCS)直接引发丙烯酸乙酯(EA)的基团转移聚合(GTP)进行了动力学跟踪,初探了该GTP反应的引发阶段、链增长阶段、链终止阶段的基础反应;三苯膦对丙烯酸乙酯的共轭加成的动力学行为;溴化锌在该反应体系的催化作用等,提出了在这种新的引发体系内的GTP反应历程。     

Atmospheric pressure photoionization for coupling liquid-chromatography to mass spectrometry: A review

This review presents the state-of-the-art techniques that couple liquid chromatography (LC) and mass spectrometry (MS) via atmospheric pressure photoionization (APPI). The different ionization mechanisms are discussed as well as the influence of the mobile phase composition, the nature of the dopant, etc. A comparison with other ionization sources, such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), is reported, and the combination of APPI with these sources is also discussed. Several applications, covering the time period of 2005-2008, for the analysis of drugs, lipids, natural compounds, pesticides, synthetic organics, petroleum derivatives, and other substances are presented.     

新型水溶性大π共轭高分子——聚吡咯｛2,5-[双(对二甲氨基苯甲烯)]｝的合成

该研究合成了一种新型水溶性大π共轭高分子———聚吡咯 ｛２ ,５ ［ 二（ 对二甲氨基苯甲烯）］｝（ＰＰＤＭＡＢ） ,它能溶于强酸的水溶液,在１ｍｏｌ／Ｌ 的盐酸中溶解度为０－５ ～１－０ｇ／１００ｍＬ．通过ＥＡ、ＸＰＳ、ＦＴ ＩＲ、ＵＶ Ｖｉｓ ＮＩＲ、Ｉｎ ｓｉｔｕ ＵＶ Ｖｉｓ ＮＩＲ 对ＰＰＤＭＡＢ进行了结构表征．通过质子化、碘掺杂、浓硫酸（９８ ％ ） 掺杂等处理,ＰＰＤＭＡＢ的电导率提高２～４ 个数量级（δ＝ １０ － ７ ～１０－ ５Ｓ／ｃｍ） ．在质子化、去质子化的过程中ＰＰＤＭＡＢ发生了可逆的颜色变化,本征态（ 综色） 质子态（ 墨兰色） ．     

电针对脑卒中后抑郁大鼠谷氨酸类神经递质及其受体的表达影响

观察电针对脑卒中后抑郁(PSD)大鼠的脑部氨基酸类神经递质表达的影响, 探讨电针治疗脑卒中后抑郁的分子机理. 将Wistar大鼠随机分为正常组、假手术组、模型组和电针治疗组, 采用夹闭颈总动脉和再通方法建立脑卒中模型. 7d后根据文献[1]方法建立PSD模型, 电针“百会”“大椎”穴, 留针20min, 1次·d-1共持续15d. 旷场试验观察其行为学表现, 免疫组织化学技术检测大鼠脑谷氨酸类神经递质的表达变化结果. 与模型组相比, 行为学实验发现电针治疗组大鼠旷场穿线抬壁次数明显增多, 差异具有统计学意义(P<0.05); 免疫组化检测发现谷氨酸及其受体NMDA/AMPA积分光密度值明显下降, 差异具有统计学意义(P<0.01). 表明电针可抑制脑卒中后抑郁大鼠脑NMDA/AMPA的表达, 这可能是电针治疗脑卒中后抑郁的分子机理之一.     

Analysis of β‐CH2 signals in the 13C NMR spectra of the methyl methacrylate–ethyl acrylate copolymer as a tool for microstructure determination

The incremental method of the chemical shift calculation in the ¹³C NMR spectra of the methyl methacrylate–ethyl acrylate copolymer, PMMA/EA, has been applied to the β‐CH₂ carbons. A positive simulation of the DEPT sub‐spectrum shows that it is possible to determine in this way the distribution of configurational‐compositional tetrads providing a tool for microstructure analysis of acrylic copolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2147–2155, 2000     

Sulforaphane Regulates eNOS Activation and NO Production via Src-Mediated PI3K/Akt Signaling in Human Endothelial EA.hy926 Cells

Sulforaphane (SFN) is a naturally occurring isothiocyanate that is abundant in many cruciferous vegetables, such as broccoli and cauliflower, and it has been observed to exert numerous biological activities. In the present study, we investigate the effect of SFN on eNOS, a key regulatory enzyme of vascular homeostasis and underlying intracellular pathways, in human endothelial EA.hy926 cells. The results indicate that SFN treatment significantly increases NO production and eNOS phosphorylation in a time- and dose-dependent fashion and also augments Akt phosphorylation in a time- and dose-dependent manner. Meanwhile, pretreatment with LY294002 (a specific PI3K inhibitor) suppresses the phosphorylation of eNOS and NO production. Furthermore, SFN time- and dose-dependently induces the phosphorylation of Src kinase, a further upstream regulator of PI3K, while PP2 pretreatment (a specific Src inhibitor) eliminates the increase in phosphorylated Akt, eNOS and the production of NO derived from eNOS. Overall, the present study uncovers a novel effect of SFN to stimulate eNOS activity in EA.hy926 cells by regulating NO bioavailability. These findings provide clear evidence that SFN regulates eNOS activity and NO bioavailability, suggesting a promising therapeutic candidate to prevent endothelial dysfunction, atherosclerosis and other cardiovascular diseases.     

Cytoprotection against Oxidative Stress by Methylnissolin-3-O-β-d-glucopyranoside from Astragalus membranaceus Mainly via the Activation of the Nrf2/HO-1 Pathway

Astragalus membranaceus is a famous herb found among medicinal and food plants in East and Southeastern Asia. The Nrf2-ARE assay-guided separation of an extract from Jing liqueur led to the identification of a nontoxic Nrf2 activator, methylnissolin-3-O-β-d-glucopyranoside (MNG, a component of A. membranaceus). Nrf2 activation by MNG has not been reported before. Using Western Blot, RT-qPCR and imaging, we investigated the cytoprotective effect of MNG against hydrogen peroxide-induced oxidative stress. MNG induced the expression of Nrf2, HO-1 and NQO1, accelerated the translocation of Nrf2 into nuclei, and enhanced the phosphorylation of AKT. The MNG-induced expression of Nrf2, HO-1, and NQO1 were abolished by Nrf2 siRNA, while the MNG-induced expression of Nrf2 and HO-1 was abated and the AKT phosphorylation was blocked by LY294002 (a PI3K inhibitor). MNG reduced intracellular ROS generation. However, the protection of MNG against the H₂O₂ insult was reversed by Nrf2 siRNA with decreased cell viability. The enhancement of Nrf2 and HO-1 by MNG upon H₂O₂ injury was reduced by LY294002. These data showed that MNG protected EA.hy926 cells against oxidative damage through the Nrf2/HO-1 and at least partially the PI3K/Akt pathways.