Alkaloids in Bufonid Toads (<Emphasis Type="Italic">Melanophryniscus</Emphasis>): Temporal and Geographic Determinants for Two Argentinian Species

Bufonid toads of the genus Melanophryniscus represent one of several lineages of anurans with the ability to sequester alkaloids from dietary arthropods for chemical defense. The alkaloid profile for Melanophryniscus stelzneri from a location in the province of Córdoba, Argentina, changed significantly over a 10-year period, probably indicating changes in availability of alkaloid-containing arthropods. A total of 29 alkaloids were identified in two collections of this population. Eight alkaloids were identified in M. stelzneri from another location in the province of Córdoba. The alkaloid profiles of Melanophryniscus rubriventris collected from four locations in the provinces of Salta and Jujuy, Argentina, contained 44 compounds and differed considerably between locations. Furthermore, alkaloid profiles of M. stelzneri and M. rubriventris strongly differed, probably reflecting differences in the ecosystem and hence in availability of alkaloid-containing arthropods.     

Meeting performance-based training demands: Accountability in an intervention-based practicum.

Describes the ways in which accountability methods were built into practicum experiences for specialist- and doctoral-level school psychology trainees at the University of Cincinnati. 13 doctoral students served as consultants to 66 3–14 yr old children who were referred by teachers and parents for academic and behavioral concerns. Four parents and 57 teachers participated in problem-solving consultation in the intervention. The results of intervention-based services were summed across individual cases developed by trainees as a means of examining the overall effectiveness of the practicum experience. Outcomes are reported as procedural adherence to the model of service delivery (operationalized as a procedural checklist), graphic analysis of the data, effect sizes, goal attainment scaling, and treatment acceptability. The methods are discussed as examples of how to meet accountability demands for training in school psychology while providing comprehensive training in the delivery of intervention-based services. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preprocessing of GNSS signals subject to interference

Increasingly, interference effects on GNSS receivers are becoming important as more safety-critical applications such as civil aviation are employing the system. The inherent interference rejection capability of the GNSS spread spectrum modulating technique is now no longer considered adequate to remove the effects of very strong jammers. These can be generated intentionally, as in jamming situations, or unintentionally by systems such as mobile satellite systems. Continuous satellite tracking through this interference is essential for high-integrity applications. This study describes a new hardware-based GNSS interference mitigation scheme which is particularly effective against CW and pulsed CW interference. Interferers with some degree of frequency or amplitude modulation can also be reduced. The core hardware can remove two CW interferers from anywhere within the GPS P code bandwidth or the GLONASS frequency spectrum and further interferers can be removed by cascading modules. Simulation and actual data are shown. Owing to the wideband nature of the signal processing, the module introduces very little additional phase distortion and thus group delay to the GLONASS band, which has been shown to be advantageous to differential GLONASS processing. © 1997 John Wiley & Sons, Ltd.     

Fluorescence and coloration of grey hair

Grey hair samples were collected from 11 individuals and separated into un‐pigmented and pigmented fibres (International Hair Importers). Fluorescence measurements were obtained by using a double‐grating fluorescence spectrophotometer and a bifurcated fibre optics accessory to measure the spectra directly from the surface of hair at various distances from the fibre root. Colour measurements were carried out by using a Hunter colorimeter. The fluorescence spectra of un‐pigmented hair obtained by the excitation at 290 nm show a peak at 356 nm [tryptophan (Trp)], and multi‐peak emissions in the range from 395 to 500 nm. A significant variation in the Trp emission intensity at 356 nm vs. the intensity of emission in the 395–500 nm range was observed for hair collected from various individuals with yellow coloured hair producing stronger relative emission in 395–500 nm range. Quantitative measurements of coloration and the calculation of the Yellowness Index (YI) showed linear correlation between YI and the ratio of fluorescence intensities I₄₄₀/I₃₅₆ The spectra obtained by excitation at 320 nm showed the emission peaks at 395 nm (unidentified), 420 nm (N‐formylkynurenine), 460 nm (kynurenine), and 495 nm (3‐hydroxykynurenine), which are the products of oxidative or metabolic conversion of tryptophan. Un‐pigmented, yellow hair showed a build‐up of the fluorescence band corresponding to 3‐hydroxykynurenine at 495 nm. The data also showed the fluorescence quenching effect of melanin resulting in the lowering of the fluorescence intensity of pigmented hair. The spectra obtained at various positions along the fibres demonstrated gradual photo‐decomposition of hair chromophores during their lifetimes. This was indicated by a decrease of Trp fluorescence intensity, which was relatively fast (8·10^?4–1.5·10^?3 [day^?1] as calculated for hair obtained from various individuals) for un‐pigmented hair and slower for pigmented hair. A decrease in Trp emission was accompanied by an increase in the yellow coloration toward the ends of un‐pigmented fibres.     

Synthesis and characterization of highly ordered cobalt-magnetite nanocable arrays

Magnetically tunable, high-density arrays of coaxial nanocables within anodic aluminum oxide (AAO) membranes have been synthesized. The nanocables consist of magnetite nanowires surrounded by cobalt nanotube sheaths and cobalt nanowires surrounded by magnetite nanotube sheaths. These materials are a combination of separate hard (Co) and soft (Fe3O4) magnetic materials in a single nanocable structure. The combination of two or more magnetic materials in such a radial structure is seen as a very powerful tool for the future fabrication of magnetoresistive, spin-valve and ultrafast spin-injection devices with nonplanar geometries. The nanocable arrays were prepared using a supercritical-fluid inclusion process, whereby the nanotube was first deposited onto the pore walls of the nanoporous membranes and subsequently filled with core material to form coaxial nanocables. In essence, this paper describes a technique for placing novel magnetic technologies into well-defined building blocks that may ultimately lead to new multifunctional devices, such as spin valves and high-density magnetic storage devices.     

19F NMR chemical shifts induced by a helical peptide

(19)F NMR spectra of two neutral, organic-soluble helical peptide octamers, each labeled at its N terminus with either 4-fluorobenzamide or 4-trifluoromethylbenzamide, in solvents with widely varying dielectric constants have been observed. The peptides are oligomers of alpha-aminoisobutyric acid (Aib), which is a residue known to form stable 3(10) helices in organic solution. In relation to the (19)F NMR spectra of a control molecule, the peptide terminating in 4-fluorobenzamide shows a solvent-dependent downfield chemical shift of between approximately 1.5 and approximately 4 ppm, whilst the peptide terminating in 4-trifluoromethylbenzamide shows only an approximately 0.2 ppm chemical shift dependence on the solvent dielectric constant. The experimental observations were compared to calculated values of the electric field generated by the correlation of dipolar amide units through the peptide's helical conformation. We find the chemical-shift response of the 4-fluorobenzamide group to the peptide's calculated electric field is consistent with the magnitude of (19)F chemical shift dispersion observed in proteins.     

An estimate of biofilm properties using an acoustic microscope

Noninvasive measurements over a biofilm, a three-dimensional (3-D) community of microorganisms immobilized at a substratum, were made using an acoustic microscope operating at frequencies up to 70 MHz. The microscope scanned a 2.5-mm by 2.5-mm region of a living biofilm having a nominal thickness of 100 microm. Spatial variation of surface heterogeneity, thickness, interior structure, and biomass were estimated. Thickness was estimated as the product of the speed of sound of the medium and the interim between the highest signal peak and that of the substratum plane without biofilm. The thickest portions of biofilm were 145 microm; however, slender structures attributed as streamers extended above, with one obtaining a 274-microm height above the substratum. Three-dimensional iso-contours of amplitude were used to estimate the internal structure of the biofilm. Backscatter amplitude was examined at five zones of increasing height from the substratum to examine biomass distribution. Ultrasound-based estimates of thickness were corroborated with optical microscopy. The experimental acoustic and optical systems, methods used to estimate biofilm properties, and potential applications for the resulting data are discussed.     

ITER Vacuum Vessel design and construction

After implementing a few design modifications (referred to as the “Modified Reference Design”) in 2009, the Vacuum Vessel (VV) design had been stabilized. The VV design is being finalized, including interface components such as support rails and feedthroughs for the in-vessel coils. It is necessary to make adjustments to the locations of the blanket supports and manifolds to accommodate design modifications to the in-vessel coils. The VV support design is also being finalized considering a structural simplification. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. The detailed layout of ferritic steel plates and borated steel plates was optimized based on the toroidal field ripple analysis. A dynamic test on the inter-modular key to support the blanket modules was performed to measure the dynamic amplification factor (DAF). An R&D program has started to select and qualify the welding and cutting processes for the port flange lip seal. The ITER VV material 316 L(N) IG was already qualified and the Modified Reference Design was approved by the Agreed Notified Body (ANB) in accordance with the Nuclear Pressure Equipment Order procedure.     

Individual and Geographic Variation of Skin Alkaloids in Three Species of Madagascan Poison Frogs (Mantella)

Alkaloid profiles for 81 individual mantellid frogs, Mantella baroni (Boulenger 1988) (N = 19), M. bernhardi (N = 51), and M. madagascariensis (Grandidier 1877) (N = 11), from six different populations from Madagascar were examined. Marked individual differences in alkaloid composition (number, type, and amount) were observed between different species and between populations of the same species. Disjunct populations of each of the three species differed significantly in alkaloid composition. Sympatric populations of M. baroni and M. madagascariensis also differed significantly in alkaloid composition. In M. bernhardi, differences in alkaloid composition were marginally associated with different sexes. A total of 111 alkaloids, including isomers, were detected in analysis of the individuals from the three species. The majority (47%) appear likely to be obtained from dietary mites, whereas many of the others (18%) are presumed to be from ants, and a few (4%) are from millipedes. Putative dietary sources for the remaining alkaloids are generally unknown, but beetles are probably the source of at least some of the tricyclic alkaloids (6%). In addition, alkaloid compositions from extracts of groups of individuals from five additional populations of M. baroni and from one population of M. bernhardi (Vences et al. 1994) and one population of M. cowanii (Boulenger 1882) were examined. An additional 50 alkaloids, including isomers, were detected in the combined samples, bringing the total number of alkaloids identified from these four species of mantellid frogs to 161. Alkaloid compositions in mantellid poison frogs are diverse and highly dependent on geographic location that appear to be largely determined by the nature and availability of alkaloid-containing prey items. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Polymer/Clay Nanocomposites: Influence of Ionic Strength on the Structure and Adhesion Characteristics in Multilayered Films

The aim of the present contribution is to understand how ionic strength, brought by the addition of salt to laponite/PEO nanocomposite dispersions, influences the texture and adhesion characteristics at nano‐ and microscales in multilayered nanocomposite films prepared from such dispersions. At the nano‐scale, SAXS and XRD measurements indicated that the clay platelets orient parallel to the film plane and that the polymer chains intercalate the clay platelets regardless of salt addition. A gradual transition from an agglomerated structure, containing polymer‐rich and clay‐rich domains, to a fine‐balanced structure with smaller distinct details without excess PEO was observed, via AFM, on the exposed edges of cryo‐microtomed films with increasing ionic strength.