Treesearch

Combining kenaf fiber with other resources provides a strategy for producing advanced composite materials that take advantage of the properties of both types of resources. It allows the scientist to design materials based on end-use requirements within a framework of cost, availability, recyclability, energy use, and environmental considerations. Kenaf fiber is a potentially outstanding reinforcing filler in thermoplastic composites. The specific tensile and flexural moduli, for example, of a 50% by volume of kenaf-polypropylene (PP) composite compares favorably with a 40% by weight of...

Bridge railing systems in the United States have historically beers designed based on static load criteria given in the American Association of State Highway and Transportation 0fficials (AASHTO) Standard Specifications for Highway Bridges. In the past decade, full-scale vehicle crash testing has been recognized as a more appropriate and reliable method of evaluating bridge railing acceptability. In 1993, the National Cooperative Highway Research Program published Report 350, Recommended Procedures for the Saftey Performance Evaluation of Highway Features, which provides new criteria for...

The structural reliability of plank decks designed by the AASHTO codes are determined. Inadequacies in load distribution and plank resistance in the current specifications are identified.

The xylose-utilizing yeast, Pichia stipitis, has a complex respiratory system that contains cytochrome and non-cytochrome alternative electron transport chains in its mitochondria. To gain primary insights into the alternative respiratory pathway, a cytochrome c gene (PsCYC1, Accession No. AF030426) was cloned from wild-type P. stipitis CBS 6054 by cross-hybridization to CYC1 from Saccharomyces cerevisiae. The 333 bp open reading frame of PsCYC1 showed 74% and 69% identity to ScCYC1 and ScCYC7, respectively, at the DNA level. Disruption of PsCYC1 resulted in a mutant that uses the salicylhy...

This paper discusses efforts to characterize the rheological properties of pulps that include low-grade wastepapers and papermill sludges to determine their potential for extrusion and conversion into useful products. We investigated apparent changes in viscosity associated with the addition of typical inorganic paper fillers (calcium carbonate, kaolin clay, and titanium dioxide) to bcleanc pulps. Addition of calcium carbonate significantly increased apparent pulp viscosity, but clay and titanium dioxide had minimal effects. When high molecular weight sodium carboxymethyl cellulose (CMC)...

The lignin peroxidases of Phanerochaete chrysosporium are encoded by a minimum of 10 closely related genes. Physical and genetic mapping of a cluster of eight lip genes revealed six genes occurring in pairs and transcriptionally convergent, suggesting that portions of the lip family arose by gene duplication events. The completed sequence of 1ipG and lipJ, together with previously published sequences, allowed phylogenetic and intron/exon classifications, indicating two main branches within the lip family. Competitive reverse transcription- PCR was used to assess lip transcript levels in...

This review summarizes patents related to paper recycling issued during the last 6 months of 1998. The two online databases used for this search are Claim/US. Patents Abstracts and Derwent World Patents Index. This semiannual feature is intended to inform readers about the latest developments in equipment, chemicals, and technology in the field of paper recycling. This review contains only brief summaries of the inventions. Readers will need to access the full texts of specific patents for complete information. We have organized this review into the following broad categories of recycling:...

A review of market history shows that southern pine sawtimber stumpage prices have increased by over 150 percent in this decade (Timber Mart South). Concurrently, some (i.e. Cubbage and Abt (1996) Nilsson et al (1999)) have questioned the adequacy of southern timber supplies to meet projected demands, which are projected to increase by about 25 percent over the next two decades. Given what we know about inventories and growth rates, what are the prospects for supplies to meet the needs of the southern pine industry?

To improve the overall performance of wood-plastic composites, appropriate technologies are needed to control moisture sorption and to improve the interaction of wood fiber with selected hydrophobic matrices. The objective of this study was to determine the surface thermodynamic characteristics of a wood fiber and to correlate those characteristics with the fiberas water vapor adsorption behavior. The surface thermodynamic properties, determined by inverse gas chromatography at infinite dilution or near zero surface coverage, were the dispersive component of the surface energy, surface...

Ultrafiltration is a potentially viable method of removing finely dispersed flexographic pigments from the deinking water loop. This work examines the effects of surface-active materials on ultrafiltration efficiency. A logarithmic relationship between permeate flax and pigment concentration was demonstrated at ink concentrations above 0.4%, permeation rates becoming independent of ink content at lower concentrations. The pressure independent ultrafiltration permeation rates observed at more highly concentrated ink dispersions were shown to be limited by mass-transfer effects, as predicted...