Jet ejection from droplets near the Leidenfrost temperature

Abstract  

Droplets impinging on a hot surface that is near the Leidenfrost temperature were experimentally investigated. Ejection of jets from the top of the droplet was observed during the transient interaction between the droplet and a hot wall. We term this phenomenon jet ejection from droplets. When the bottom of the droplet initially impacts the hot surface, a jet is to be ejected from the top of the droplet. The jet ejection occurred only at low impact velocities and around the wetting limit temperature. It was not observed when droplets were dropped from large heights or when the surface was at a high temperature.     

DNA sensor: A novel electrochemical gene detection method using carbon electrode immobilized DNA probes

Abstract

The authors have developed a novel, rapid, convenient, and specific gene detection method, named the ‘DNA sensor,’ using a graphite electrode loaded with DNA probes. Synthesized oligonucleotide (5-TGCAGTTCCGGTGGCTGATC-3′) complementary to oncogene v-myc was employed for a model probe. The oligonucleotide was chemically adsorbed on a basal plane pyrolytic graphite (BPPG) electrode. The sensor was able to be applied to a hybridization reaction (40°C) in a linearized pVM623 solution carrying the Pst I fragment of v-myc (1.5 kbp).

After the hybridization reaction, the sensor was immersed into an acridine orange solution (1 μM) and washed with a phosphate buffer (pH 7.0). Acridine orange intercalated between base pairs of the formed double stranded DNAs on the electrode. The anodic peak potential of acridine orange that interacted with the DNAs on the electrode was measured. The positive shift of the peak potential increased in proportional to the pVM623 concentration in the hybridization reaction. 10^?1 g/ml of pVM623 was able to be detected in the buffer solution using the sensor. This gene detection was completed within an hour.     

Biosynthetic Conclusions from the Functional Dissection of Oxygenases for Biosynthesis of Actinorhodin and Related Streptomyces Antibiotics

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Highlights? ActVA-ORF5 is a flavin-dependent monooxygenase required for actinorhodin biosynthesis ? ActVA-ORF5 and its three close homologs were functionally dissected ? ActVA-ORF5 and Gra-21 are bifunctional at C-6/C-8, while Med-7 acts only for C-6 ? AlnT exhibits different regiospecificity for oxidation of tricyclic substrates     

A screw-shaped alignment of pyrene using m-calix[3]amide

m-Calix[3]amide bearing three pyrenes (1a) was prepared by the condensation reaction of 3-nonylaminobenzoic acid derivative using Ph₃PCl₂. Pyrenyl groups were found to be aligned in the screw-like fashion by m-calix[3]amide as confirmed by the X-ray crystallography. Aromatic proton signals observed at the up-field region in the ¹H NMR spectrum at low temperature indicated that pyrenyl groups in 1a are aligned in close proximity in THF solution. UV–vis absorption and fluorescence emission spectra did not show marked peak shift nor concentration fluorescence quenching compared with reference compounds implying no significant electronic interaction between pyrenyl groups. These results can be explained by the steric effect of the m-calix[3]amide platform. On the other hand, an excimer emission was observed for m-calix[3]amide having a flexible spacer between pyrene and m-calix[3]amide (1b).     

Photoaddressable polymers for liquid crystal alignment

We demonstrate reversible photoinduced in situ reorientation of low molecular mass liquid crystals (LCs) by means of photoaddressable polymers (PAPs). These polymers contain mesogenic azobenzene side chains optimized to reorient cooperatively and effectively upon illumination with polarized light. Various low molecular mass LCs were introduced between two PAP layers and these sandwich devices were tested with respect to stability and reversibility of photoinduced orientation. Dissolution of the PAP layer by the low molecular mass LC was observed for several material combinations and systematically investigated. Different anisotropic dyes were added as fluorescence markers in order to monitor the photoinduced LC orientation. With an optimized material combination, more than 10 reversible reorientation processes could be realized with polarized light of either 514 or 405 nm wavelength, without any reduction in alignment quality. Further, microscopic polarized fluorescence patterns could be produced and erased within short exposure times.