DNA‐Based Peroxidation Catalyst—What Is the Exact Role of Topology on Catalysis and Is There a Special Binding Site for Catalysis?

In the last decade, there has been growing interests in studies aimed at delineating the strategies used by various nucleic acid enzymes to facilitate catalysis. Insights gained from such studies would enable the design of better DNA/RNA catalysts for various applications such as biosensing. DNA and RNA catalysts have been shown to be able to catalyze myriads of reactions, including peroxidation reactions, which are catalyzed by G-quadruplexes. In this report, we provide data that clarifies how G-quadruplex peroxidases achieve catalysis. Firstly, we show that by covalently linking a hemin cofactor to DNAzymes, anti-parallel G-quadruplexes, which have been previously shown to be catalytically inefficient, can be "resurrected" to become good peroxidation catalysts. We also reveal that the relative rates of peroxidation by DNAzyme peroxidases depend on the nature of the organic reductant, arguing for a special binding site in the peroxidase-mimicking DNAzymes for catalysis.     

Thiazole orange-induced c-di-GMP quadruplex formation facilitates a simple fluorescent detection of this ubiquitous biofilm regulating molecule

Recently, there has been an explosion of research activities in the cyclic dinucleotides field. Cyclic dinucleotides, such as c-di-GMP and c-di-AMP, have been shown to regulate bacterial virulence and biofilm formation. c-di-GMP can exist in different aggregate forms, and it has been demonstrated that the polymorphism of c-di-GMP is influenced by the nature of cation that is present in solution. In previous work, polymorphism of c-di-GMP could only be demonstrated at hundreds of micromolar concentrations of the dinucleotide, and it has been a matter of debate if polymorphism of c-di-GMP exists under in vivo conditions. In this Article, we demonstrate that c-di-GMP can form G-quadruplexes at low micromolar concentrations when aromatic molecules such as thiazole orange template the quadruplex formation. We then use this property of aromatic molecule-induced G-quadruplex formation of c-di-GMP to design a thiazole orange-based fluorescent detection of this important signaling molecule. We determine, using this thiazole orange assay on a crude bacterial cell lysate, that WspR D70E (a constitutively activated diguanylate cyclase) is functional in vivo when overexpressed in E. Coli . The intracellular concentration of c-di-GMP in an E. Coli cell that is overexpressed with WspR D70E is very high and can reach 2.92 mM.     

Surface-enhanced Raman scattering and DFT investigation of Eriochrome Black T metal chelating compound

The surface-enhanced Raman scattering (SERS) spectra of Eriochrome Black T (EBT) and its Cu(II), Fe(III), Mn(II) and Pb(II) complexes were recorded using a hydroxylamine reduced silver colloid. Molecular geometry optimization, molecular electrostatic potential (MEP) distribution and vibrational frequencies calculation were performed at B3LYP/6-31G(d) level of theory for the EBT molecule and its Cu(EBT), Fe(EBT) and Mn(EBT) metal complexes. Differentiation between EBT complexes of Cu(II), Fe(III), Mn(II) and Pb(II) is shown by the SERS spectral features of each complex.     

Complete assignment of the vibrational modes of C60 by inelastic neutron scattering spectroscopy and periodic-DFT

In this paper we exploit the complementarity of inelastic neutron scattering (INS), infrared and Raman spectroscopies with ab initio calculations to generate an updated assignment of the vibrational modes of C(60). We have carried out periodic-DFT calculations of the high temperature face centred cubic phase modelled as the standard structure and also of the low temperature simple cubic phase, the latter for the first time. Our assignment differs from all previous work, however, it is the only one that is able to successfully reproduce the INS spectrum in terms of both transition energies and intensities. In addition to the INS spectrum we are also able to quantitatively simulate the major features of the infrared and Raman spectra in the high temperature phase and the infrared spectrum in the low temperature phase.     

具有苯烷基侧链的芳香液晶聚酯的合成及性质

以熔融缩聚方法全盛了具有苯烷基侧链取代的全芳香液晶聚酯，用TG，DSC，热台偏光显微镜研究了聚酯的热性能，并讨论了取代基对聚酯热性能的影响，所有合成的聚酯均为热致型液晶，且具有较低的相转变温度。特别是当聚对苯二甲酸对苯二酚酯的两个苯环上分别取代了叔丁基和苯烷基，或取代了两个苯烷基侧链后，聚酯的熔融温度下降到225℃以下，并可在室温下溶于普通的有机溶剂中。     

Integrated band intensities in N2O4 in the infrared range

We have measured the integrated band intensities of the ν₉ and ν₁₁ bands of N₂O₄ which are observed around 1757 and 1261 cm^-1, respectively. By varying temperature and pressure, we have obtained: S_band(ν₉) = 9.60(130), 9.10(24), 8.80(66) and S_band(ν₁₁)= 5.93(64), 5.70(21) and 5.33(46) (in 10^-17 cm/molecule) at 293.15 (60), 277.25 (60) and 261.65 (60) K, respectively.     

On the angular dependence of gaps in 1-D Si/SiO2 periodic structures

A multilayer of silicon and silicon dioxide was used to study the angular dependence of reflectance maxima originating from interference and bulk optical properties. Silicon dioxide has a lattice resonance in the infrared causing an interval of high reflectance for wavelengths around 9 μm. The multilayer was designed such that the interference maxima do not overlap/interact with the material related reflectance maximum. In this way the different angular behavior for the two types of reflectance maxima can be studied simultaneously. Experimental and calculated reflectance spectra for s- and p-polarized light for angles of incidence between 0° and 90° collected for every 5° are presented. The reflectance features caused by interference generally move to shorter wavelengths with increasing angle of incidence, and the materials related peak is widened for (s-polarized light) and excitation of the longitudinal modes was observed for p-polarized light.