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Core-corona structures of poly(ethyleneoxide)/polybutadiene (PEO/PB) block copolymer micelles are directly resolved for the first time by examining rapidly vitrified samples by transmission electron microscopy at liquid nitrogen temperature (Cryo-TEM). Spherical micelles form at higher PEO/PB block volume ratio; cylindrical form at lower block volume ratio. Images of both shapes of micelles show a dense core and a diffuse corona. The core and corona sizes agree well with theoretical prediction from the "star" model of polymer micelles.

Transition of vesicles to micelles induced by flow of dilute aqueous cetyltrimethylammonium chloride (CTAC)/ sodium 3-methylsalicylate (CH 3 Sal -) dispersion was directly imaged by rapidly vitrifying small ultrathin specimens after varying periods of postflow on-the-grid relaxation, and then examining them by cryogenictemperature transmission electron microscopy (cryo-TEM). Vesicles prevail in quiescent equimolar 5 mM dispersions of CTAC and NaCH 3 Sal at equilibrium. When the dispersions are deformed and strained by rapid drainage of the excess from the specimens, the vesicles transform into an entangled network of threadlike micelles. The micelles revert to vesicles with time after drainage flow ceases. Intermediate structures during the transition were also captured by cryo-TEM. We hypothesize that the straining actions of flow disrupt vesicles, distort the distribution of, or strip, the counterions around vesicle fragments, shift the binding and dissociation equilibrium of counterions, alter the local preferred curvature of the surfactant assemblies, and thus induce structural instability of the fragments that leads to their reconstruction into networks of branching threadlike micelles.

This is a computational modeling study of a cold atmospheric pressure helium plasma jet impinging on a dielectric surface placed normal to the jet axis. This study provides insights into the propagation mechanism of the plasma jet, the electrical properties, and the total accumulated charge density at the dielectric surface. For the radial streamer propagation along the dielectric surface, Penning ionization and the electron impact ionization of helium atoms are the major ionization reactions in the streamer head, while Penning ionization is the only dominant contributor along the streamer body. In addition, the plasma bullet velocity along the dielectric surface is 10–100 times lower than that in the plasma column. Increasing tube radius or helium flow rate lowers air entrainment in the plasma jet, leading to a decrease of the radial electric field and the accumulated charge density at the dielectric surface. Furthermore, the tube radius has weaker influence on the plasma properties as tube radius increases. For a target dielectric with lower relative permittivity, a higher radial electric field penetrates into the material, and the surface ionization wave along the dielectric surface extends farther. Higher relative permittivity of the treated dielectric results in more charging at the dielectric surface and more electron density in the plasma column.

Both mu opioid (MOP) † and type 2 cholecystokinin (CCK 2 ) receptors are present in areas of the central nervous system that are involved in modulation of pain processing. We conducted bioluminescence resonance energy transfer (BRET) studies on COS cells coexpressing MOP and CCK 2 receptors to determine whether receptor heterodimerization is involved in such modulation. These studies revealed the absence of constitutive or monovalent ligand-induced heterodimerization. Heterodimerization of MOP and CCK 2 receptors therefore is unlikely to be responsible for the opposing effects between morphine and CCK in the CNS. However, association was induced, as indicated by a positive BRET signal, on exposure of the cells to bivalent ligands containing muopioid agonist and CCK 2 receptor antagonist pharmacophores linked through spacers containing 16 to 22 atoms, but not with a shorter (9-atom) spacer. These studies demonstrate for the first time that an appropriately designed bivalent ligand is capable of inducing association of G protein-coupled receptors. The finding that opioid tolerance studies with these ligands in mice showed no correlation with the BRET data is consistent with the absence of association of MOP and CCK 2 receptors in vivo.

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Spinal mGluR3 activation or mGluR5 inhibition reduced bone cancer pain. Inhibition of spinal astrocyte activation may contribute to the analgesic effects. These findings may lead to novel strategies for the treatment of bone cancer pain.

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