Ventral tegmental area dopamine neurons mediate the shock sensitization of acoustic startle: A potential site of action for benzodiazepine anxiolytics.

Dopamine (DA)-containing neurons in the ventral tegmental area (VTA) are thought to play an important role in fear motivation. The primary objective of the present study was to determine the connection between DA D?, gamma aminobutyric acid (GABA)A, and benzodiazepine receptors in the VTA and footshock-associated emotionality. Microinfusion of the DA D? receptor agonist quinpirole, the GABAA receptor agonist muscimol, and the benzodiazepine receptor agonist flurazepam into the VTA was observed to suppress the shock enhancement of acoustic startle amplitudes. None of the drugs depressed baseline startle responding or footshock reactivity. The results indicate the involvement of VTA DA neurons in the fear-arousing properties of footshock and implicate the VTA as a possible neural site for the anxiolytic actions of benzodiazepines. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced proteolytic activity of covalently bound enzymes in photopolymerized sol gel

Trypsin is covalently linked to a photopolymerized sol-gel monolith modified by incorporating poly(ethylene glycol) (PSG-PEG) for on-column digestion of N(alpha)-benzoyl-l-arginine ethyl ester (BAEE) and two peptides, neurotensin and insulin chain B. The coupling of the enzyme to the monolith is via room-temperature Schiff chemistry in which an alkoxysilane reagent (linker) with an aldehyde functional group links to an inactive amine on trypsin to form an imine bond. The proteolytic activity of the immobilized trypsin was measured by monitoring the formation of N alpha-benzoyl-L-arginine (BA), the digestion product of BAEE. The BA is separated from BAEE by capillary electrophoresis and detected downstream (18.5 cm from the microreactor) by absorption (254 nm). Using the Bradford assay, we determined that 97 ng of trypsin is bound to the 1-cm microreactor located at the entrance of capillary column. The bioactivity of the trypsin-PSG-PEG microreactor at 20 degrees C for the digestion of BAEE was found to be 2270 units/mg of immobilized trypsin. The bioactivity of trypsin bound to the capillary wall in the open segment upstream from the monolith was 332 units/mg of immobilized trypsin under the same conditions. In contrast, the activity of free trypsin could not be observed for the digestion of BAEE at 20 degrees C after 16 h of incubation time.     

Novel Nanorod Precipitate Formation in Neodymium and Titanium Codoped Bismuth Ferrite

The discovery of unusual nanorod precipitates in bismuth ferrite doped with Nd and Ti is reported. The atomic structure and chemistry of the nanorods are determined using a combination of high angle annular dark field imaging, electron energy loss spectroscopy, and density functional calculations. It is found that the structure of the BiFeO₃ matrix is strongly modified adjacent to the precipitates; the readiness of BiFeO₃ to adopt different structural allotropes in turn explains why such a large axial ratio, uncommon in precipitates, is stabilized. In addition, a correlation is found between the alignment of the rods and the orientation of ferroelastic domains in the matrix, which is consistent with the system's attempt to minimize its internal strain. Density functional calculations indicate a finite density of electronic states at the Fermi energy within the rods, suggesting enhanced electrical conductivity along the rod axes, and motivating future investigations of nanorod functionalities.     

Universal temperature model for shallow algal ponds provides improved accuracy

While temperature is fundamental to the design and optimal operation of shallow algal ponds, there is currently no temperature model universally applicable to these systems. This paper presents a model valid for any opaque water body of uniform temperature profile. This new universal model was tested against 1 year of experimental data collected from a wastewater treatment high rate algal pond. On the basis of 1 year of data collected every 15 min, the average errors of the predicted afternoon peak and predawn minimum were both only 1.3 °C and the average error between these extremes was just 1.2 °C. In order to demonstrate the improvement in accuracy gained, the expressions for heat fluxes used in nine prior temperature models were systematically substituted into the new universal model and evaluated against the experimental data. Errors in the peak and minimum temperatures increased by up to 2.1 and 3.2 °C, respectively, while the error between these extremes increased by up to 2.9 °C. In practical applications, these levels of inaccuracies could lead to an under/overestimation of the algal productivity and the evaporative water loss by approximately 40% and 300%, respectively.     

Ultrasonic evaluation of geometrical and surface parameters of rough defects in solids

Ultrasonic measurements from rough cracks were carried out using both broad-band and narrow-band methods. An analysis is suggested to determine parameters of the crack quantitatively such as size, shape, rms surface roughness, and distribution function of the surface roughness. Ultrasonic measurements of the parameters compare very well with the actual parameters of the defect.     

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