Morphology and concentration of smoke from fluorinated ethylene propylene wire insulation in microgravity under forced airflow.

The production of smoke particles from the jet bursting flame caused by overheating fluorinated ethylene propylene (FEP) wire insulations was investigated. Experiments examining the morphology and volume fraction of the fractal smoke particle aggregates with forced airflow were conducted in a 3.5s drop tower. Gravity level and forced flow were shown to have significant hydrodynamic effects on the pathlines and fractal aggregation of the smoke particles, thus the residence time-dependent flame shape, particle size and concentration have obvious changes. For cases in still air, compared with normal gravity, the jet flame in microgravity has a spherical shape, the mean primary particle and aggregate gyration radius are bigger due to longer residence time, but the fractal dimension maintains at about 1.79, similar to that in the normal gravity level; the calculated smoke volume fraction is also bigger. For cases with force flow in microgravity, the mean primary particle diameter, the mean aggregate gyration radius, and soot volume fraction all decrease with increasing forced flow due to decreasing residence time.

One-pot synthesis of GO/AgNPs/luminol composites with electrochemiluminescence activity for sensitive detection of DNA methyltransferase activity.

DNA methyltransferases catalyze the transfer of a methyl group from S-adenosylmethionine to the target adenine or cytosine, eventually inducing the DNA methylation in both prokaryotes and eukaryotes. Herein, we developed a novel electrochemiluminescence biosensor to quantify DNA adenine methylation (Dam) methyltransferase (MTase) employing signal amplification of GO/AgNPs/luminol composites to enhance the assay sensitivity. The method was developed by designing a capture probe DNA, which was immobilized on gold electrode surface, to hybridize with azide complementary DNA to form the azide-terminated dsDNA. Then, alkynyl functionalized GO/AgNPs/luminol composites as the signal probe were immobilized to azide-terminated dsDNA modified electrode via click chemistry, resulting in a high electrochemiluminescence (ECL) signal. Once the DNA hybrid was methylated (under catalysis of Dam MTase) and further cleaved by Dpn I endonuclease (a site-specific endonuclease recognizing the duplex symmetrical sequence of 5'-G-Am-T-C-3'), GO/AgNPs/luminol composites release from the electrode surface to the solution, leading to significant reduction of the ECL signal. The change of the ECL intensity is related to the methylation status and MTase activity, which forms the basis of MTase activity assay and site-specific methylation determination. This novel strategy can be further used as a universal method for other transferase determination by designing various transferase-specific DNA sequences. In addition, this method can be used for the screening of antimicrobial drugs and has a great potential to be further applied in early clinical diagnosis.

Bis(4-ferrocenylbenzoato-κO)tetra-kis(methanol-κO)cadmium(II).

The complete mol-ecule of the title compound, [CdFe(2)(C(5)H(5))(2)(C(12)H(8)O(2))(2)(CH(4)O)(4)], is generated by crystallographic twofold symmetry, with the Cd atom lying on the rotation axis. The Cd atom is coordinated by the O atoms of the four methanol mol-ecules and by the O atoms of the two carboxyl-ate anions (the latter in cis geometry), resulting in a distorted CdO(6) octa-hedron. The phenyl-ene ring is almost coplanar with its adjacent cyclo-penta-dienyl ring [dihedral angle = 8.2 (2)°]. The uncoordin-ated carboxyl-ate O atom acts as acceptor to two O-H⋯O hydrogen bonds from the methanol mol-ecules, giving rise to a layered network.