Potentiometric biosensor employing catalytic antibodies as the molecular recognition element

Catalytic antibodies are introduced as an important new class of biomolecules for molecular recognition in biosensors in which the binding sites are continually regenerated by the catalytic reaction of the substrate. Consequently, molecular recognition by catalytic antibodies can yield reversible immunoblosensors. In this example, a prototype potentiometric biosensor is described in which a micro-pH electrode is modified with a catalytic antibody that catalyzes the hydrolysis of phenyl acetate, producing hydrogen ions that can be monitored by the electrode. The reversible response is linear with the log of substrate concentration over a range of 20-500 microM with a detection limit of 5 microM under the conditions of this study. Alternative applications of catalytic antibodies in other biosensor configurations are discussed.     

High‐strength biodegradable poly(vinyl alcohol)/fly ash composite films

We prepared biodegradable composite films of poly(vinyl alcohol) (PVA) and fly ash (FA) spanning 5, 10, 15, 20, and 25 wt % concentrations by casting aqueous solutions. The tensile strengths of the composite films were increased proportionally via the addition of FA. The strength of the film was enhanced by 193% with 20% FA compared to the neat PVA control. Further addition of FA deviated from the linear trend. The moduli of the composites also increased proportionally with FA addition to 212% at 20 wt % FA addition compared to the control. The percentage strain at break exponentially decreased with the addition of FA. In the dynamic mechanical behavior, the storage and loss moduli both increased with FA content. The tan δ peaks corresponding to the glass‐transition temperature shifted 5–10°C higher above the control sample (73°C). This shift was attributed to a reduction in the mobility of PVA segments because they were anchored by the FA surface. The reductions in mobility manifested in strong interfacial interactions were indicative of hydrogen bonding. Broadening and reduction in the intensities of the stretching and bending peaks of ? OH, ? CH and ? C?O of PVA in the Fourier transform infrared spectra were observed. This suggested that hydrogen bonding was active between the functional groups in the FA and PVA chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparison of Biological and Chemical Predictors of Dermal Carcinogenicity of Petroleum Oils

Various methods have been proposed as a basis for cancer hazard labelling of petroleum products. The Institute of Petroleum analytical method termed IP 346/80 was recently recommended to the European Union as the preferred method for this purpose. In this report we compare IP 346/80 with several other predictors of dermal carcinogenicity, including the Mobil PAC Method, the Modified Ames Test (ASTM Method E 1687-95), and the ^32P-postlabelling assay for DNA adducts. Oils for assay were selected from a repository of samples previously subjected to mouse skin-painting bioassay. 120 oils were tested in the Modified Ames Assay, 57 by the Mobil PAC Method, 50 by Method IP 346/80, and 48 by the postlabelling procedure. The ability of each assay to distinguish between carcinogenic and noncarcinogenic oils was examined at various suggested discriminators, e.g. Mutagenicity Indices (MI) of 1.0 and 2.0, 3-7 ring PAC contents of 1% and 2% (w/w), and IP 346/80 DMSO-extractables of 2% and 3% (w/w). Various adduct levels were tested for maximum discrimination between carcinogenic and noncarcinogenic oils. The accuracy of each method is reported.     

Benefits of a high‐performance phosphite in the gamma irradiation of polyolefins

The highly active process stabilizer bis(2,4‐dicumylphenyl)pentaerythritol diphosphite (P1) was compared in a series of polyolefin formulations with tris(2,4‐di‐t‐butylphenyl) phosphite (P2). Because of its high activity, there was less polymer degradation during processing with P1 as compared to P2. As a result, improvements in color and other physical properties were observed for the polymers, not only during processing, but also after treatment with gamma radiation.     

Purification and crystallization of complexes modeling the active state of the fragile histidine triad protein

Fragile histidine triad protein (Fhit) is a diadenosine triphosphate (ApppA) hydrolase encoded at the human chromosome 3 fragile site which is frequently disrupted in tumors. Reintroduction of FHIT coding sequences to cancer cell lines with FHIT deletions suppressed the ability of these cell lines to form tumors in nude mice even when the reintroduced FHIT gene had been mutated to allow ApppA binding but not hydrolysis. Because this suggested that the tumor suppressor activity of Fhit protein depends on substrate-dependent signaling rather than ApppA catabolism, we prepared two crystalline forms of Fhit protein that are expected to model its biologically active, substrate-bound state. Wild-type and the His96Asn forms of Fhit were overexpressed in Escherichia coli, purified to homogeneity and crystallized in the presence and absence of ApppA and an ApppA analog. Single crystals obtained by vapor diffusion against ammonium sulfate diffracted X-rays to beyond 2.75 A resolution. High quality native synchrotron X-ray data were collected for an orthorhombic and a hexagonal crystal form.      

Suitability of Dynamic Modeling for Flood Forecasting during Ice Jam Release Surge Events

Ice jam release surges present a unique challenge to the flood forecaster, since the surge released when an ice jam fails is highly dynamic in nature and, therefore, traditional hydrologic flood routing techniques are inapplicable. The problem is analogous to the classic dam break scenario and should be amenable to analysis by hydraulic flood routing techniques. However, previous investigations suggest that the influence of ice on the wave propagation and attenuation must also be considered to achieve accurate results. This study explores the applicability of dynamic hydraulic flow modeling techniques to the ice jam surge propagation problem, presenting the results of numerical simulations of the ice jam release event which occurred on the Saint John River upstream of Grand Falls, N.B., in April 1993. The surge propagation analysis was conducted using a one-dimensional finite element implementation of the Saint Venant equations adapted for natural channel geometries. Even neglecting ice effects, the resulting model is successful in terms of reproducing the observed peak stage and the surge propagation speed. Based on these results, it is concluded that accurate channel geometry is a key factor in effectively modeling ice jam release surge events.