Segregation of dopamine and glutamate release sites in dopamine neuron axons: regulation by striatal target cells.

Dopamine (DA) is a key regulator of circuits controlling movement and motivation. A subset of midbrain DA neurons has been shown to express the vesicular glutamate transporter (VGLUT)2, underlying their capacity for glutamate release. Glutamate release is found mainly by DA neurons of the ventral tegmental area (VTA) and can be detected at terminals contacting ventral, but not dorsal, striatal neurons, suggesting the possibility that target-derived signals regulate the neurotransmitter phenotype of DA neurons.

Universal method for the fabrication of detachable ultrathin films of several transition metal oxides.

Ultrathin films are important nanoscale structures that are used extensively in a variety of technological contexts. However, it has traditionally been difficult and costly to fabricate detachable and purely inorganic high aspect ratio films with controlled thickness and good uniformity. Here we report a versatile method to make separable purely inorganic membranes of various metal oxides such as Nb(2)O(5), TiO(2), WO(3), and Ta(2)O(5) with thicknesses ranging from 30 to 150 nm.

Nanopatterning of transition metal surfaces via electrochemical dimple array formation.

Nanoscale surface patterning is of great importance for applications ranging from catalysts to biomaterials. We show the formation of ordered nanoscale dimple arrays on titanium, tungsten, and zirconium during electropolishing, demonstrating versatility of a process previously only reported for tantalum. This is a rare example of an electrochemical pattern formation process that can be translated to other materials.

Biomimetic synthesis of gold nanocrystals using a reducing amphiphile.

The first synthesis of a chelating and reactive surfactant derived from citric acid and a short silicone as hydrophobic tail is described. Aqueous solutions of this reactive amphiphile spontaneously induce gold ion reduction, particle nucleation, and further direct crystal growth. The process, both pH and light dependent, occurs through lipid-directed assembly of metal ions, their reduction and subsequent lipid-directed growth to yield ultrathin (approximately 7 nm thick) quasi two-dimensional gold nanocrystals.

Roughening of gold atomic steps induced by interaction with tetrahydrofuran.

Exposure of a clean gold surface to tetrahydrofuran (THF) under ambient conditions was observed to cause roughening of atomic step edges. This change was followed in situ using a scanning tunneling microscope during the exposure of a gold surface to a controlled stream of THF vapor. THF is a common solvent used in depositing molecules, self-assembled monolayers, and polymer films on surfaces, in electrochemistry, and in chemical reactions.

Robust inorganic membranes from detachable ultrathin tantalum oxide films.

We report a simple electrochemical method of making individual free-standing and uniform tantalum oxide membranes between 35 and 100 nm thick. These films can be separated, floated on water, and transferred onto various substrates such as Si wafers, glass slides, and TEM grids. Our membranes are mechanically, chemically, and thermally robust, have a high dielectric constant, and a high refractive index, making them potentially useful in sensors, optics, filtration, and catalysis.

Formation of highly ordered arrays of dimples on tantalum at the nanoscale.

We show that electropolishing of tantalum metal in a single step of about 5 min can reproducibly lead to dimples tens of nanometers in diameter, regular in shape, monodispersed in size, and arranged in highly ordered arrays which even transverse grain boundaries. Dimpled tantalum is ductile, high melting, and chemically inert, which makes it suitable for nanostructure synthesis even under extreme conditions, as demonstrated with a simple sputter coating and flame annealing procedure for gold nanoparticles.