Magnetic Leakage Internal Detection Device and Series-Parallel Detection Method for Small Diameter Ferromagnetic Spiral Heat Exchanger Tubes

Based on the calculation of magnetic circuit of the detection probe, this article designs a kind of magnetic leakage detection device and series-parallel detection method of small diameter spiral heat exchange tube to realize the safety detection of small diameter spiral heat exchange tube. The detection device includes a detection probe and a probe drive mechanism, which drives the detection probe to move in the spiral heat exchange tube. The detection probe includes an intermediate connector, a magnetizer which is arranged coaxially at both ends of the intermediate connector in turn, a steel ball support body and an end connector. The designed detection probes are mixed in series and parallel, and multiple detection probes are put together in series to be placed in a spiral heat exchange tube to form a group of detection probes in series. Then, multiple groups of detection probes in series are placed in each spiral heat exchange pipe, forming a series-parallel combination, which can detect multiple spiral heat exchange pipes at the same time and improve the detection efficiency greatly

Redox-Responsive Hyperbranched Poly(amido amine)s with Tertiary Amino Cores for Gene Delivery

Redox-responsive hyperbranched poly­(amido amine)­s (PAAs) with tertiary amino cores and amine, poly­(ethylene glycol) (PEG) and hydroxyl terminal groups were prepared for DNA delivery respectively. The DNA condensation capability of PAAs was investigated using gel electrophoresis, and the results showed that PAA terminated with 1-(2-aminoethyl)­piperazine (AEPZ) (BAA) is the most efficient in binding plasmid DNA (pDNA). The diameter and zeta-potential of polyplexes from PAAs were characterized using dynamic light scattering (DLS), and the morphology of the polyplexes was obtained using atomic force microscopy (AFM). All the PAAs were able to condense pDNA into nanoparticles with diameters between 50 and 200 nm with a positive surface charge when the weight ratio of polymer/DNA was higher than 20. Glutathione (GSH)-induced DNA release from polyplexes and the buffering capability of PAAs were investigated as well. Cytotoxicity of PAAs and <i>in vitro</i> gene transfection of polyplexes were evaluated in HEK293, COS-7, MCF-7 and Hep G2 cell lines, respectively. The results reflect that PAAs show remarkably low or even no cytotoxicity, and that PAA with amino terminal groups mediates the most efficient gene transfection with the transfection efficiency comparable to that of 25 kDa polyethylenimine. Further the effects of the presence of buthionine sulfoximine (BSO) on the transfection efficiency and cytotoxicity of BAA polyplexes were investigated