Pathogenicity of three species of entomopathogenic nematodes to some major stored-product insect pests

Entomopathogenic nematodes (Nematoda: Heterorhabditidae and Steinernematidae) are commonly used biological control agents of insects in cryptic habitats, but their potential for suppressing stored-product insects in these habitats has not been explored previously. Here, we provide data from the first step in a program to evaluate entomopathogenic nematodes in the genus Steinernema as biological control agents of stored-product pests by determining their pathogenicity to some of the major stored-product pest species. When evaluated against larvae, pupae and adults of six pest species (Plodia interpunctella, Ephestia kuehniella, Oryzaephilus surinamensis, Tenebrio molitor, Tribolium castaneum, and Trogoderma variabile), and the adults of two additional pest species (Sitophilus oryzae and Rhyzopertha dominica), Steinernema riobrave was either the most pathogenic or of similar pathogenicity compared to S. carpocapsae and S. feltiae. A dose of 10 infective juveniles of S. riobrave caused 80% or higher mortality against larvae of P. interpunctella, E. kuehniella, T. castaneum, and O. surinamensis, pupae of T. castaneum and T. molitor, and adults of T. molitor and the two moth species. All stages of Trogoderma variabile exhibited 70% or higher mortality. Adults of S. oryzae and R. dominica exhibited low susceptibility with 15% and 35% mortality, respectively. On the basis of these results, S. riobrave was selected for further evaluation under more field-like conditions.     

Degradation of polyethylene terephthalate films in the presence of lubricants for HFC 134a: a critical issue for hermetic motor insulation systems

Earlier studies conducted in the use of sealed tubes with polyalkylene glycol lubricants and polyethylene terephthalete (PET) films revealed that the PET films exhibited embrittlement and (visual) degradation. This led to an investigation of PET embrittlement mechanisms with the new lubricants used with HFC 134a. The lubricants studied were three polypropylene glycols (the monol, the diol and the completely end-capped glycols), pentaerythritol ester and a blend of monol and ester. The effects of moisture content, temperature and lubricant structure were studied. All lubricants in this study were of viscosity grade ISO-32 (150 SUS). The results were compared to PET film embrittlement in the presence of CFC 12 and mineral oil. This study reconfirmed the earlier findings that the PET films must be dried to lower than 0.1 wt.% moisture content for use in hermetic systems. This paper discusses the effect of the moisture content of the lubricant and the effect of the lubricant structure on PET films. The dependence of the various mechanisms on temperature is shown. Esters and end-capped polyalkylene glycols are recommended for use with HFC 134a.     

Mathematical analysis of viscometric (polymer) flow fields in capillaries: Taylor dispersion revisited

A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation.     

Ceramics for Prosthetic Hip and Knee Joint Replacement

The most commonly used bearing couple in prosthetic hip or knee joint replacements consists of a cobalt–chrome (CoCr) metal alloy articulating against ultrahigh-molecular-weight polyethylene. Ceramics have been used as an alternative to metal-on-polyethylene in joint replacement surgery of arthritic hips and knees since the 1970s. In prosthetic hip and knee bearings, ceramic surfaces offer a major benefit of drastically reduced wear rates and excellent long-term biocompatibility, which can increase the longevity of prosthetic hip and knee joints. This benefit is important clinically because hip and knee replacement has become a very common surgical procedure, particularly in the United States, and because these procedures are being increasingly performed in younger patients who place greater demands on the prosthetic bearings. However, ceramics are brittle and the risk of catastrophic bearing failure in vivo , while rare, is a major concern. Improvements in material quality, manufacturing methods, and implant design have resulted in a drastic reduction of the incidence of such failures, so that modern ceramic bearings are safe and reliable if used with components of proven design and durability. Future material improvements are actively being investigated to reduce the risk of ceramic-bearing failures even further. The purpose of this article is to review the structure, properties, applications, and limitations of the ceramics that have been used in orthopedic bearings, and to describe the new ceramic composite materials and surface treatments that will be available for joint replacement surgery in the near future.     

Early Stages of Calcium Phosphate Formation on Bioactive Borosilicate Glass in Aqueous Phosphate Solution

The conversion of bioactive glass to a calcium phosphate material, typically hydroxyapatite (HA), by solution–precipitation reactions in aqueous phosphate solution, has been commonly reported. This paper describes the structural and compositional characteristics of the calcium phosphate material formed during the early-stage conversion (<5 h) of a borosilicate glass (designated H12) in aqueous phosphate solution. Disks of H12 glass were reacted with 0.25 M K₂HPO₄ solution with a starting pH=7.0 at 37°C. The structure and composition of the product layer were characterized using thin film X-ray diffraction, scanning electron microscopy, and Fourier transform infrared reflectance spectroscopy. For reaction times <5 h, the results indicated the formation of brushite (CaHPO₄·2H₂O) with coarse, plate-like crystals. In comparison, the formation of HA with small needle-like crystals was found at later times. This early-stage formation of brushite has not been reported in previous studies of converting bioactive silicate and borate glasses in aqueous phosphate solution.     

Evaluation of the degree of cure of a coating

Coating cure is compared using pencil hardness, MEK rubs, and thumb twist test to evaporation rate analysis (ERA). ERA is rated most objective and reproducible. Department of Polymer Science, Hattiesburg, MS. Rockville, MD.     

A networked mobile sensor test-bed for collaborative multi-target tracking applications

This paper presents the design, architecture, implementation, and experimental results from a networked mobile sensor test-bed developed for collaborative sensor tracking applications. The test-bed comprises a fleet of networked mobile sensors, an indoor localization system, a control, debugging and management infrastructure, and a tiered wireless ad hoc network for seamless integration of the above three components and the existing wireless infrastructure. First, the software and hardware architectural details of a swarm capable autonomous vehicle (SCAV) system for our collaborative applications are presented. Second, the details of an indoor self-localization and Kalman filter based navigation system design for the SCAV platform are presented. Third, as an example multi-sensor application, a collaborative multi-target tracking problem and a heuristics-based networked solution are formulated. Finally, the performance of the collaborative tracking framework is evaluated on the laboratory test-bed for characterizing the impacts of localization and navigation errors on the distributed tracking performance. The experimental study also characterizes the tradeoff between the tracking performance and the consumed wireless bandwidth. The experimental results demonstrate a number of counterintuitive results due to various errors in sensor localization and navigation.     

US Foreign Affiliates,Technology Diffusion and Host Country Human Development: Human Development Index versus Human Capital

In this study, we use a cross-sectionally correlated and timewise autoregressive model and panel data for the period 1966–2000 to investigate human development as a measure of host country absorptive capacity in 30 developed and developing countries. The results suggest that technology diffusion from US foreign affiliates has a positive and significant impact on labor productivity only if host countries have a minimum level of human development. This condition may partially explain why previous studies show mixed support for the hypothesis that foreign affiliates have a positive effect on productivity in developing countries. Although the results have to be interpreted with caution, the policy implication is that human development enhances the capacity of countries to reap the benefits of foreign direct investments.