Electroretinographic analysis of ultraviolet sensitivity in juvenile and adult goldfish retinas

Electroretinographic (ERG) spectra show that juvenile goldfish have ultraviolet (UV) sensitivity but adults do not. Chromatic adaptation data suggest mediation by UV cones. ERG spectra from eye cups and spectrophotometry of lenses show that the loss of UV sensitivity with age does not result from lens changes. Our results contribute to a growing literature on UV cone mechanisms and visual development in fish.     

Misinterpretation of body sensations in panic disorder

Cognitive accounts of panic predict that panic disorder patients will be particularly prone to misinterpret autonomic sensations. Several studies have produced results consistent with this prediction, but each is open to alternative interpretation. To clarify matters, 2 studies administered the Body Sensations Interpretation Questionnaire (BSIQ) to panic patients and controls. Panic patients were more likely to interpret ambiguous autonomic sensations as signs of immediately impending physical or mental disaster and were more likely than other anxiety disorder patients and nonpatients to believe these interpretations. In a 3rd study, a brief version of the BSIQ was shown to have satisfactory test-retest reliability, to change with treatment, and to discriminate treatments that varied in their effects on panic.     

The solubility of methane in aqueous solutions of monoethanolamine,diethanolamine and triethanolamine

The solubility of methane in 3 kmol/m³ solutions of monoethanolamine, diethanolamine, and triethanolamine was measured from 25° to 125°C and pressures up to about 13 MPa. Measurements were also made for the solubility of methane in water at 25° to 125°C and pressures up to 18 MPa in order to confirm the accuracy of the experimental technique. It is demonstrated that methane is more soluble (in terms of mole fraction) in the amine solution than in pure water. Furthermore, the solubility is an increasing function of the size of the alkanolamine. The solubility data were modeled using a Henry's-law approach and the results summarized in terms of salting-in coefficients.     

Synthesis of ‘ready-to-adsorb’ polymeric nanoshells for magnetic iron oxide nanoparticles via atom transfer radical polymerization

Polymer-magnetite nanoparticle complexes that respond to both magnetic fields and to temperature have been demonstrated. Novel alkyl halide-functional bis(diethylphosphonate) esters were prepared and utilized as initiators for polymerizing N-isopropylacrylamide by controlled atom transfer radical polymerization. The phosphonate esters were removed after polymerization to afford poly(N-isopropylacrylamide) with a bis(phosphonic acid) moiety precisely placed at one terminus. The bis(phosphonic acid) endgroups were adsorbed onto magnetite nanoparticles to yield nanoscale complexes that were stable against any polymer desorption and that were colloidally-stable in physiological media. Thus, the bis(phosphonate) endgroup provides a robust anchoring moiety onto the magnetite. Hydrodynamic sizes of the complexes were predicted with a density distribution model and using the measured sizes of the magnetite cores. Good agreement between the measured and predicted hydrodynamic sizes suggested that the complexes were primarily discrete, non-agglomerated nanoparticles. The complexes exhibited thermosensitive aggregation behavior near the lower critical solution temperature of the poly(N-isopropylacrylamide) component.     

Integrator backstepping techniques for the tracking control ofpermanent magnet brush DC motors

An integrator backstepping technique is introduced for the design of high-performance motor controllers. The approach is applied to the design of embedded computed torque and output feedback controllers for permanent magnet brush DC (BDC) motors. The proposed controllers are simulated and experimentally verified on a user-developed digital signal processor (DSP) based data acquisition and control (DAC) system. Although the BDC motor is well researched, the results motivate extensions of the proposed techniques to the development of similar controllers for more complex electromechanical systems, such as separately excited DC, permanent magnet stepper, brushless DC, switched reluctance, and AC induction servo motors     

Vinyl chloride in rural water from pre‐1977 applications of PVC pipe

In the early 1990s, vinyl chloride monomer (VCM) was found in a rural water system that included poly(vinyl chloride) (PVC) pipe manufactured prior to 1977. Because VCM, considered a human carcinogen, was not regulated in pipe until 1977, some pre‐1977 pipes could contain it at significant levels. Manufacturing processes adopted in 1975 and in place by 1977 reduced VCM levels by as much as a factor of 1000. Pipe manufactured by using the newer resin technology does not show detectable VCM migration under any reasonable installation circumstances. Migration of VCM is a function of pipe size, VCM concentration at time of installation, water temperature, and flow rate. History, scientific investigations, and conclusions drawn from field investigations are summarized. Tools for the determination of possible candidate systems, potential noncompliance, and remediation, both short‐term and long‐term, are provided. A spreadsheet‐based computer model of diffusion is described.     

Polyhydrides of Sc,Zr and Hf and Their Proposed Formation.

Hydrogenation at 500 psi of (PNP)Sc(CH₃)₂ results in formation of a trinuclear polyhydride complex [(PNP)Sc]₃(μ₂-H)₄(μ₃-H)₂ ( 1 ) in 55 % yield. The solid-state structure shows a non-symmetric trinuclear species resulting from one pincer phosphine arm being demetallated, and where two hydrides bridge all three Sc centers, whereas the other four bridge two. Hydrogenation of (PNP)Zr(CH₃)₃ at 200 psi results instead in formation of a dinclear polyhydride species [(PNP)Zr(H)]₂(μ₂-H)₄ ( 2 ). Conducting the hydrogenation at atmospheric pressure, resulted instead in formation of the bridging methylidene complex [(PNP)Zr(CH₃)]₂(μ₂-H)₂(μ₂-CH₂) ( 3 ), which cleanly converted to 2 , upon hydrogenation at higher pressure. Both 2 and 3 were also structurally characterized. Hydrogenation of (PNP)Hf(CH₃)₃ at 200 psi resulted in incomplete hydrogenation with some formation of dinuclear mono- and dimethyl-polyhydride complexes [(PNP)Hf(CH₃)]₂(μ₂-H)₄ ( 4 ) and [(PNP)Hf(CH₃)][(PNP)Hf(H)](μ₂-H)₄ ( 5 ), which were identified by solid-state X-ray structural studies. Based on these results, we propose a pathway for the complete hydrogenation of (PNP)Zr(CH₃)₃ to 2 .     

Effects of dietary casein and soy protein on metabolism of radiolabelled low density apolipoprotein B in rabbits

Rabbits fed semipurified diets containing casein have elevated plasma cholesterol levels compared to those fed soy protein. As part of continuing studies on the mechanism of casein-induced hypercholesterolemia, two groups of six rabbits were fed these diets for 14 to 16 weeks. Animals fed the casein diet were found to have significantly higher plasma concentrations of protein, cholesterol, triacylglycerol, phospholipid and apolipoprotein B (apo B) associated with low density lipoprotein (LDL) than those fed the soy protein diet. Kinetic studies showed that the fractional catabolic rate of LDL-apo B was significantly lower in animals fed casein than in those fed soy protein regardless of whether the tracer LDL was obtained from donors fed casein or soy protein. The production rate of LDL-apo B was higher in casein-fed animals but this was not statistically significant. These results show that the efficiency of removal of LDL is significantly reduced in animals fed casein compared to those fed soy protein, and that the source of LDL did not affect the efficiency of its subsequent removal. The acumulation of LDL in casein-fed animals is consistent with down-regulation of the LDL receptor.     

Recycled carbon fiber filled polyethylene composites

Composites of recycled carbon fiber (CF) with up to 30 wt % loading with polyethylene (PE) were prepared via melt compounding. The morphology of the composites and the degree of dispersion of the CF in the PE matrix was examined using scanning electron microscopy, and revealed the CF to be highly dispersed at all loadings and strong interfacial adhesion to exist between the CF and PE. Raman and FTIR spectroscopy were used to characterize the surface chemistry and potential bonding sites of recycled CF. Both the Young's modulus and ultimate tensile stress increased with increasing CF loading, but the percentage stress at break was unchanged up to 5 wt % loading, then decreased with further successive addition of CF. The effect of CF on the elastic modulus of PE was examined using the Halpin‐Tsai and modified Cox models, the former giving a better fit with the values determined experimentally. The electrical conductivity of the PE matrix was enhanced by about 11 orders of magnitude on addition of recycled CF with a percolation threshold of 7 and 15 wt % for 500‐μm and 3‐mm thick samples. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008