Three coordination polymers of 5-aminoisophthalic acid with similar benzimidazole derivative ligands: synthesis,structure and DNA-binding studies

Three novel coordination polymers, [Co(NH₂-Aip)(H₂Bibim)] _n (1), [Co(NH₂-Aip)(HBibimop)] _n  √ nH₂O (2) and [Mn(NH₂-Aip) √ H₂O] _n  √ 2nH₂O (3) with NH₂-Aip and similar benzimidazole derivative ligands (NH₂-Aip = 5-aminoisophthalic acid, H₂Bibim = 2,2′-bibenzimidazole and HBibimop = 1,3-bis(benzimidazol-2-yl)-2-oxapropane), have been synthesised under hydrothermal conditions and structurally characterised by single-crystal X-ray diffraction analysis, elemental analysis and IR spectroscopy. 5-Aminoisophthalic acid ligand adopts μ₂-, μ₃- and μ₄-bridge coordination fashion and benzimidazole derivatives exist as terminal- and bridge-mode in complexes 1–3. The intricate hydrogen bonds and π–π stacking interactions in supramolecular framework are discussed. Using the combination of ultraviolet–visible absorption titration and fluorescence spectra, the experimental results show that complexes 1 and 2 bind to DNA in an intercalative mode and their DNA-binding constants (K _b ) are also found.     

Laterally dibenzyloxy-branched nematogens with large nematic range and rich solid polymorphism

Mesogenic compounds containing four rings in the core usually have very high melting points. However, when two identical lateral benzyloxy groups are introduced on the same side of one of the central rings, the melting point is lowered dramatically and a large nematic range is retained. This range is affected by the bulkiness of the para-substituents in the lateral rings. Methyl groups can be introduced in the ortho- or meta-positions with a consequent decrease in the melting temperature without much affecting the nematic range. These compounds exhibit a rich solid polymorphism which is certainly related to the effect of the conformations of the lateral substituent on the molecular arrangment in the solid phase. Some preliminary NMR experiments on the nematic phase indicate that the molecular long axis coincides with the core axis, whereas the para-axis of the lateral fragment makes an angle close to the magic angle with respect to the molecular long axis.     

基于IFCM-GRA的空间多维热误差温度测点优化

热误差是精密、超精密加工中主要的误差源之一,热误差温度测点优化是热误差补偿的关键问题.在机床空间多维布置的大量温度测点之间存在多重相关性,从众多测点中选取特征点的优劣程度,将直接影响到热误差补偿效果.通过对温度测点间多重相关性及温度与热误差关系的综合分析,采用改进的模糊C-均值(IFCM)聚类算法对温度测点进行聚类,以减小类与类之间温度测点的相关性,且避免FCM算法对初始聚类中心敏感易局部收敛的缺点.对温度测点按灰色关联分析(GRA)中的灰色综合关联度进行排序,从变化量和变化率的角度综合反映温度与热误差的关系.采用IFCM-GRA对温度测点进行优化,提高了热误差模型的鲁棒性及准确性,使温度测点数量大幅度减少.在某型号精密卧式加工中心上进行实验,温度测点从17个减少到4个.在不同转速下,利用多元线性回归对优化出的温度测点与热误差建立模型,所建立模型均能很好地预测热误差变化情况,经对预测模型分析,轴向热误差由几十微米减小到5μm以内.     

Synthesis,photophysical properties and DFT studies of 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl)hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile dye

The chromophore 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl) hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile (PPHTCF) was synthesized through coupling of diazotized 3-amino-4,6-dimethyl-5-nitropyrazolo[3,4-b]pyridine with 3-cyano-2-(dicyanomethylene)-4,5,5-trimethylfuran (TCF). The absorption solvatochromism behaviour of PPHTCF, in various solvents, presented ΔE_max = +5.40 where the positive sign suggested red shift occurrence, implying that the PPHTCF has more polar lowest excited state than its ground one. While, the PPHTCF fluorescence spectra afforded λ_em, in 575–633 nm range, and was more dependent on the solvent polarity than the absorption λ^max, despite both exhibited red shift by 58 and 42 nm, respectively. To discover the PPHTCF solvatochromism behaviour in term of “Stokes’ shift”, both of Lippert-Mataga and linear solvation-energy relationship (LSER) formulations have been utilized and the outcomes endorsed that the later was better than the former (R² = 0.9728). Finally, TD-DFT simulated absorption and emission spectra in EtOH revealed that λ^max has been resulted mainly from HOMO → LUMO; HOMO-5 → LUMO and HOMO-2 → LUMO transitions, respectively.     

Anti-corrosion and anti-microbial evaluation of novel water-soluble bis azo pyrazole derivative for carbon steel pipelines in petroleum industries by experimental and theoretical studies

In this research, we investigated the synthesis of a novel water-soluble bis azo pyrazolin-5-one (ABP) which was synthesized efficiently via the regioselective reaction of hydrazine with coumarin hydrazone (CMH). Also, we evaluate their anti-corrosion and anti-bacterial behavior. The inhibition efficiency of ABP in an acidic medium (1.0 M HCl) was evaluated using various electrochemical and surface morphology measurements. The novel bis pyrazole-based azo dye ABP (16 × 10^?6 M) demonstrated a higher protection capacity (93.3 %). Tafel curves revealed that ABP was a mixed-type inhibitor. The adsorption of ABP on the C-steel (CS) surface is proven by the alteration in (R_ct and C_dl) impedance characteristics and obeyed the Langmuir isotherm model. SEM/EDX, AFM, and XPS surface examinations confirmed the enhancement of an adsorbed film protects the CS surface from acid corrosion at the appropriate dose. Furthermore, theoretical calculations using DFT and MC simulations were performed to identify the active sites on ABP molecules in charge of the adsorption and surface protection of the CS. The adsorption of bis pyrazole-based azo dye on the metal surface explained the protection mechanism. Moreover, the ABP screened for its antimicrobial activity against sulfate-reducing bacteria (SRB), and the calculated inhibition efficiency was 100 %. The current work presents significant results in manufacturing and producing novel water-soluble bis pyrazole-based azo dye derivative with high anti-corrosion and anti-microbial efficiency.     

基于模糊概率符号有向图的复杂系统故障诊断

通过分析复杂系统的故障信息传递特性,在符号有向图(SDG)中引入了状态关联概率和模糊信息,并结合面向对象技术提出了一种新的故障描述模型--模糊概率有向图.给出了基于此模型的建模方法和诊断流程.进一步引入消息节点和支路,通过连接各子实体对象的模糊概率SDG模型,构成整个复杂系统的模糊概率SDG系统.该模型能对复杂系统故障诊断中存在的复杂关联关系进行建模与故障诊断.利用该方法建立了某武器平台的故障诊断系统,实验结果表明提出的方法有效且实用.     

数据挖掘技术在数控机床可靠性分析中的应用

数控装备的可靠性研究的故障模式及影响分析方法通常采用频率法,该分析方法效果良好但过于繁琐。为此,采用数据挖掘技术中的关联规则方法,找出零(元)部件或系统可能发生故障原因和故障模式,为故障模式分析提供有效的方法。并给出关联规则算法的具体步骤。实例证明,该方法实用,有效。     

Single-Molecule Analysis Determines Isozymes of Human Alkaline Phosphatase in Serum

Alkaline phosphatase (ALP) is an important biomarker, as high levels of ALP in blood can indicate liver disease or bone disorders. However, current clinical blood tests only measure the total concentration of ALP but are unable to distinguish enzyme isotypes. Here, we demonstrate a novel and rapid approach to profile various ALP isozymes in blood via a single-molecule-analysis platform. The microarray platform provides enzyme kinetics of hundreds of individual molecules at high throughput. Using these single molecule kinetics, we characterize the different activity profiles of ALP isotypes. By analyzing both healthy and disease samples, we found the single molecule activity distribution of ALP in serum reflects the health status of patients. This result demonstrates the potential utility of the method for improving the conventional ALP test, as well as for analyzing other enzymatic biomarkers, including enzyme isotypes.     

Association behavior of linear ω-functionalized polybutadienes in cyclohexane

The dilute solution properties of linear polybutadienes with dimethylamine and zwitterionic end groups were studied by membrane osmometry (MO), low-angle laser light scattering (LALLS), viscometry, and dynamic light scattering (DLS) in cyclohexane. The polymers were prepared by anionic polymerization, under high vacuum conditions using [3-(dimethylamino)propyl]lithium as initiator. The dimethylamine groups were converted to zwitterions by reaction with cyclopropane sultone. No evidence of association was found for the amine-capped polymers, whereas the zwitterionic samples exhibited strong association in cyclohexane. The degrees of association increase by decreasing molecular weight of the base polymer due to the excluded volume repulsions. These aggregation numbers are of the same order as those found for ω-functionalized polyisoprenes, with the same polar groups in the same solvent. The hydrodynamic properties, measured by viscometry and dynamic light scattering, supported the conclusions drawn by LALLS and provide strong evidence that the aggregates behave hydrodynamically as star polymers. Comparison with theoretical models shows that the association behavior is best described by the linear head packing model. © 1996 John Wiley & Sons, Inc.