Deoxyribozyme-based ligase logic gates and their initial circuits

A complete set (YES, NOT, AND, and ANDNOT) of molecular scale logic gates based on ligase deoxyribozymes was constructed. The activity of these gates was visualized through the formation of cascades with downstream phosphodieseterase YES gates, which performed fluorogenic cleavage.     

Monitoring the effect of ultrafast deactivation of the electronic excited states of DNA bases and polynucleotides following 267 nm laser excitation using picosecond time-resolved infrared spectroscopy

In this paper we demonstrate the use of picosecond time-resolved infrared spectroscopy (ps-TRIR) to monitor the early structural dynamics of DNA bases and polydeoxynucleotides following UV excitation in solution.     

Analysis of ochres from Clearwell Caves: the role of particle size in determining colour

Three ochre samples (A (orange-red in colour), B (red) and C (purple)) from Clearwell Caves, (Gloucestershire, UK) have been examined using an integrated analytical methodology based on the techniques of IR and diffuse reflectance UV-visible-NIR spectroscopy, X-ray diffraction, elemental analysis by ICP-AES and particle size analysis. It is shown that the chromophore in each case is haematite. The differences in colour may be accounted for by (i) different mineralogical and chemical composition in the case of the orange ochre, where higher levels of dolomite and copper are seen and (ii) an unusual particle size distribution in the case of the purple ochre. When the purple ochre was ground to give the same particle size distribution as the red ochre then the colours of the two samples became indistinguishable. An analysis has now been completed of a range of ochre samples with colours from yellow to purple from the important site of Clearwell Caves.     

Electrochemical studies on three polar diruthenium(II,III) complexes

Electrochemical studies on a new class of diruthenium(II,III) compounds were done. The complexes having a polar arrangement of ligands across the diruthenium unit in Ru₂Cl(hp)₄(Hhp), Ru₂Cl(chp)₄ and Ru₂Cl(PhNpy)₄ where Hhp, Hchp and PhNHpy are 2-hydroxypyridine, 6-chloro-2-hydroxypyridine, and 2-anilinopyridine, respectively, undergo two or more oxidations and reductions. The metal centered reductions in the range of +0.1 to ?0.75 V and oxidations in the range +0.5 to +1.2 V are discussed and compared with diruthenium carboxylato and amidato complexes.     

Regio‐ and Enantio‐selective Chemo‐enzymatic C−H‐Lactonization of Decanoic Acid to (S)‐δ‐Decalactone

The conversion of saturated fatty acids to high value chiral hydroxy‐acids and lactones poses a number of synthetic challenges: the activation of unreactive C?H bonds and the need for regio‐ and stereoselectivity. Here the first example of a wild‐type cytochrome P450 monooxygenase (CYP116B46 from Tepidiphilus thermophilus) capable of enantio‐ and regioselective C5 hydroxylation of decanoic acid 1 to (S)‐5‐hydroxydecanoic acid 2 is reported. Subsequent lactonization yields (S)‐δ‐decalactone 3 , a high value fragrance compound, with greater than 90 % ee. Docking studies provide a rationale for the high regio‐ and enantioselectivity of the reaction.     

Covalent Attachment of Fibronectin onto Emulsion‐Templated Porous Polymer Scaffolds Enhances Human Endometrial Stromal Cell Adhesion,Infiltration, and Function

A novel strategy for the surface functionalization of emulsion‐templated highly porous (polyHIPE) materials as well as its application to in vitro 3D cell culture is presented. A heterobifunctional linker that consists of an amine‐reactive N‐hydroxysuccinimide ester and a photoactivatable nitrophenyl azide, N‐sulfosuccinimidyl‐6‐(4′‐azido‐2′‐nitrophenylamino)hexanoate (sulfo‐SANPAH), is utilized to functionalize polyHIPE surfaces. The ability to conjugate a range of compounds (6‐aminofluorescein, heptafluorobutylamine, poly(ethylene glycol) bis‐amine, and fibronectin) to the polyHIPE surface is demonstrated using fluorescence imaging, FTIR spectroscopy, and X‐ray photoelectron spectroscopy. Compared to other existing surface functionalization methods for polyHIPE materials, this approach is facile, efficient, versatile, and benign. It can also be used to attach biomolecules to polyHIPE surfaces including cell adhesion‐promoting extracellular matrix proteins. Cell culture experiments demonstrated that the fibronectin‐conjugated polyHIPE scaffolds improve the adhesion and function of primary human endometrial stromal cells. It is believed that this approach can be employed to produce the next generation of polyHIPE scaffolds with tailored surface functionality, enhancing their application in 3D cell culture and tissue engineering whilst broadening the scope of applications to a wider range of cell types.     

Modified and environmentally friendly oxidation of phosphorane ylides to vicinal tricarbonyls using unsupported moist Oxone in dichloromethane

Abstract

Modified and eco-friendly oxidation of phosphorane ylides to the corresponding vicinal tricarbonyls (VTC) using unsupported moist Oxone in dichloromethane at room temperature is described. This green oxidation protocol is simple, mild, and highly efficient to operate, and allowing a chemoselective preparation of VTC from various phosphorane ylides without tedious workup procedures of extraction/drying process in excellent yields.     

Stepwise elongation effect on the two-photon absorption of self-assembled butadiyne porphyrins

Butadiyne-porphyrin dimer arrays, which were generated by complementary coordination of the central zinc atom to imidazolyl followed by metathesis, were elongated stepwise and their 2PA properties were explored.     

Photo‐oxidative Stress Impacts the Expression of Genes Encoding Iron Metabolism Components in Chlamydomonas†

Chlamydomonas, like other organisms, regulates iron assimilation very tightly through differential expression of iron assimilation components. Nevertheless, in the presence of excess iron, cells do overaccumulate iron but without an evident phenotype. As iron toxicity is attributed to reactive oxygen species, we tested the impact of photon flux density (PFD) on cells with increased iron content. We noted that growth at >500 μmol m^?2 s^?1 is inhibited as iron content of the medium is increased, suggesting that high light exacerbates the systems of iron toxicity and vice versa. Cells grown in high light selectively down‐regulate the abundance of iron assimilation components, ferroxidase and FEA1, and storage protein ferritin1. At the RNA level, the abundance of ferroxidase (FOX1), iron reductase (FRE1), iron assimilatory protein (FEA1) and ferritin (FER1) mRNAs is also decreased. The time course of the response to high light compared to the response to Rose Bengal and H₂O₂ treatments suggests that both singlet oxygen and H₂O₂ may be implicated in the high light response. This hypothesis is supported by the recapitulation of some but not all of the high light responses in the carotenoid‐deficient, high light–sensitive npq1lor1 strain. We conclude that responses to iron nutrition and PFD are connected, and the determination of an optimum for photosynthetic growth for each is dependent on the other. This work defines a fourth stage of iron nutrition in Chlamydomonas, the iron excess situation, which can be molecularly and physiologically distinguished from the iron‐limited, iron‐deficient and iron‐replete stages, described previously.     

Rheological complexity in simple chain models

Dynamical properties of short freely jointed and freely rotating chains are studied using molecular dynamics simulations. These results are combined with those of previous studies, and the degree of rheological complexity of the two models is assessed. New results are based on an improved analysis procedure of the rotational relaxation of the second Legendre polynomials of the end-to-end vector in terms of the Kohlrausch-Williams-Watts (KWW) function. Increased accuracy permits the variation of the KWW stretching exponent beta to be tracked over a wide range of state points. The smoothness of beta as a function of packing fraction eta is a testimony both to the accuracy of the analytical methods and the appropriateness of (eta(0)-eta) as a measure of the distance to the ideal glass transition at eta(0). Relatively direct comparison is made with experiment by viewing beta as a function of the KWW relaxation time tau(KWW). The simulation results are found to be typical of small molecular glass formers. Several manifestations of rheological complexity are considered. First, the proportionality of alpha-relaxation times is explored by the comparison of translational to rotational motion (i.e., the Debye-Stokes-Einstein relation), of motion on different length scales (i.e., the Stokes-Einstein relation), and of rotational motion at intermediate times to that at long time. Second, the range of time-temperature superposition master curve behavior is assessed. Third, the variation of beta across state points is tracked. Although no particulate model of a liquid is rigorously rheologically simple, we find freely jointed chains closely approximated this idealization, while freely rotating chains display distinctly complex dynamical features.