Electrochemical Characterization of a Porous Pt Nanoparticle ＂Nanocube-Mosaic＂ Prepared by a Modified Polyol Method with HCI Addition

Porous and single crystalline platinum (Pt) nanoparticles (NPs) have been successfully synthesized by reduction of H₂PtCl₆·6H₂O and then investigated by optical spectroscopy and transmission electron microscopy. H₂PtCl₆·6H₂O was reduced using ethylene glycol in the presence of polyvinylpyrrolidone under highly acidic conditions (pH < 1) to form single crystalline Pt particles about 5 nm in size. These particles were then stacked via {100} facets, forming 50-nm length porous nanocubes with a mosaic structure. The porous Pt NPs exhibited excellent catalytic properties for methanol oxidation. In particular, the electrochemical surface area was ∼63 m²/g, five times higher than that for non-porous Pt NPs prepared using a conventional method. We suggest that the high catalytic activity of porous Pt NPs is due to a combination of the crystalline structure having exposed {100} facets and a porous morphology.      

Species-specific PCR-based assays for the detection of Fusarium species and a comparison with the whole seed agar plate method and trichothecene analysis

Species-specific PCR was used for the identification of nine Fusarium species in pure mycelial culture. A PCR-based method was compared with the whole seed agar plate method and trichothecene analysis for three toxin-producing Fusarium species using 85 grain samples of wheat, barley, oat, corn and rye. A simple SDS-based DNA extraction system followed by potassium acetate precipitation resulted in consistent PCR amplification of DNA fragments from cultures and grain samples. The species-specific PCR assays correctly identified pure cultures of Fusarium avenaceum ssp. avenaceum (9 isolates), Fusarium acuminatum ssp. acuminatum (12 isolates), Fusarium crookwellense (7 isolates), Fusarium culmorum (12 isolates), Fusarium equiseti (11 isolates), Fusarium graminearum (77 isolates), Fusarium poae (10 isolates), Fusarium pseudograminearum (23 isolates), and Fusarium sporotrichioides (10 isolates). Multiplex PCR was developed for the simultaneous detection of F. culmorum, F. graminearum and F. sporotrichioides, the three most important trichothecene producing species in Canada. In grain samples, results of PCR assays for these same three species related well with whole seed agar plate method results and determination of Fusarium trichothecenes. The PCR assay described in this study can be used for routine detection and identification of Fusarium spp. in Canada.     

Ability of alcoholics to escape detection by the MMPI.

The ability of two groups of respondents to dissimulate successfully on special alcohol scales and validity measures of the Minnesota Multiphasic Personality Inventory (MMPI) was evaluated. Forty White male alcohol-dependent inpatients and 40 matched nonalcoholic general medical patients each completed the MMPI twice: once under instructions to answer honestly and once under dissimulation instructions. Results showed that, under honest conditions, any of six special alcohol scales had a hit rate of about 80%. In the dissimulation condition, both alcoholic and medical patients were capable of producing significantly more benign profiles on both the general clinical and the special alcohol scales. However, the Positive Malingering (Mp) and Social Desirability (Sd) dissimulation scales were able to detect approximately 80% of the deceptive profiles, whereas others were somewhat less accurate. When the best dissimulation scale (Mp) and the best special alcohol scale (MacAndrew; MAC) were used in this study, only 3 of 40 dissimulating alcoholics were not identified as either alcoholics or dissimulators. Implications for use of the MMPI as an instrument for alcoholism screening are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Research into the Bioengineering of a Novel α-Conotoxin from the Milked Venom of Conus obscurus

The marine cone snail produces one of the fastest prey strikes in the animal kingdom. It injects highly efficacious venom, often causing prey paralysis and death within seconds. Each snail has hundreds of conotoxins, which serve as a source for discovering and utilizing novel analgesic peptide therapeutics. In this study, we discovered, isolated, and synthesized a novel α3/5-conotoxins derived from the milked venom of Conus obscurus (α-conotoxin OI) and identified the presence of α-conotoxin SI-like sequence previously found in the venom of Conus striatus. Five synthetic analogs of the native α-conotoxin OI were generated. These analogs incorporated single residue or double residue mutations. Three synthetic post-translational modifications (PTMs) were synthetically incorporated into these analogs: N-terminal truncation, proline hydroxylation, and tryptophan bromination. The native α-conotoxin OI demonstrated nanomolar potency in Poecilia reticulata and Homo sapiens muscle-type nicotinic acetylcholine receptor (nAChR) isoforms. Moreover, the synthetic α-[P9K] conotoxin OI displayed enhanced potency in both bioassays, ranging from a 2.85 (LD₅₀) to 18.4 (IC₅₀) fold increase in comparative bioactivity. The successful incorporation of PTMs, with retention of both potency and nAChR isoform selectivity, ultimately pushes new boundaries of peptide bioengineering and the generation of novel α-conotoxin-like sequences.     

Fiber orientation in simple injection moldings. Part I: Theory and numerical methods

This paper sets out the theory and numerical methods used to simulate filling and fiber orientation is simple injection moldings (a film-gated strip and a center-gated disk). Our simulation applies to these simple geometry problems for the flow of a generalized Newtonian fluid where the velocities can be solved independently of fiber orientation. This simplification is valid when the orientation is so flat that the fibers do not contribute to the gapwise shear stresses. A finite difference solution calculates the temperature and velocity fields along the flow direction and through the thickness of the part, and fiber orientation is then integrated numerically along pathlines. Fiber orientation is three-dimensional, using a second-rank tensor representation of the orientation distribution function. The assumptions used to develop the simulation are not valid near the flow front, where the recirculating fountain flow complicates the problem. We present a numerrical scheme that includes the effect of the fountain flow on temperature and fiber orientation near the flow front. The simulation predicts that the orientation will vary through the thickness of the part, causing the molding to appear layered. The outer “skin” layer is predicted only if the effects of the fountain flow and heat transfer are included in the simulation.