Treesearch

A missing element of paper aging research is a description of mechanical performance with aging. Tensile strength cannot be predicted directly from DP measurements, and existing models do not represent the effects of aging on strength and stiffness. The primary aim of the present work is to characterize changes of mechanical properties, such as tensile response and dimensional stability, with aging and to develop time-dependent models to describe the behavior of paper components in stamp laminates. This includes understanding the underlying mechanisms of aging, such as changes of fiber...

Fungal lignin-degrading systems likely include membrane-associated proteins that participate in diverse processes such as uptake and oxidation of lignin fragments, production of ligninolytic secondary metabolites, and defense of the mycelium against ligninolytic oxidants. Little is known about the nature or regulation of these membrane-associated components. We grew the white rot basidiomycete Phanerochaete chrysosporium on cellulose or glucose as the carbon source and monitored the mineralization of a 14C-labeled synthetic lignin by these cultures to assess their ligninolytic competence....

Orientation of adjacent genes has been reported to affect their expression in eukaryotic systems, and metabolic engineering also often makes repeated use of a few promoters to obtain high expression. To improve transcriptional control in heterologous expression, we examined how these factors affect gene expression and enzymatic activity in Saccharomyces cerevisiae. We assembled D-xylose reductase (XYL1)and D-xylitol dehydrogenase (XYL2) in four ways. Each pair of genes was placed in two different tandem (1 > 2> or

Dynamics of single curved fiber sedimentation under gravity are simulated by using the lattice Boltzmann method. The results of migration and rotation of the curved fiber at different Reynolds numbers are reported. The results show that the rotation and migration processes are sensitive to the curvature of the fiber.

The objective of this study was to evaluate the possibility of simplification of the process. The question in focus was simply whether phosphortriamidates impregnated wood would be as effective concerning fire resistance and fungal decay as phosphoramidate bonded wood.

Pressure-sensitive adhesives (PSAs) in recovered paper reduce efficiency and increase operating costs for paper recycling mills. Increased PSA fragmentation during pulping and the corresponding reduction in screening efficiency are indications that a PSA will likely interfere with paper recycling. Water-based PSAs, which dominate the label market, have complex formulations that include several amphiphilic materials, i.e., emulsifiers, dispersants, and wetting agents. Increasing the amount of these surface-active materials increased adhesive fragmentation during pulping, and thus reduced...

Part I of this paper identifies timberland areas in 12 western states where thinning treatments are judged to be needed to reduce fire hazard and may ?pay for themselves?? at a scale to make investment in forest product processing a realistic option. We also estimate amounts of biomass removed and costs of removal. Part II of this paper estimates the market impact if biomass is supplied from treatments on federal land. In Part I, a web-based tool -Fuel Treatment Evaluator 3.0 -was used to select high fire hazard timberland plots from the Forest Service Forest Inventory and Analysis Program...

This chapter reviews applications of Raman spectroscopy in the field of wood and pulp fibers. Most of the literature examined was published between 1998 and 2006. In addition to introduction, this chapter contains sections on wood and components, mechanical pulp, chemical pulp, modified/treated wood, cellulose I crystallinity of wood fibers, and the self-absorption phenomenon in near-infrared (IR) Fourier-transform (FT)-Raman spectroscopy. When needed, the sections are further categorized into various subsections. For example, the section on wood and components contains a variety of topics...

Trichoderma reesei is the main industrial source of cellulases and hemicellulases used to depolymerize biomass to simple sugars that are converted to chemical intermediates and biofuels, such as ethanol. We assembled 89 scaffolds (sets of ordered and oriented contigs) to generate 34 Mbp of nearly contiguous T. reesei genome sequence comprising 9,129 predicted gene models. Unexpectedly, considering the industrial utility and effectiveness of the carbohydrate-active enzymes of T. reesei, its genome encodes fewer cellulases and hemicellulases than any other sequenced fungus able to hydrolyze...

A modified fiber-orientation tester uses polarization processing of reflected light from paper to provide both surface and subsurface fiber-orientation angles. This makes possible both thickness-direction and cross-machine-direction profiling. Results obtained from two Fourdrinier machines show that subsurface angles are not well represented by a trended average of felt and wire surface angles. In fact, they can lie outside the range of surface angles and change sign unexpectedly. Sign changes suggest that the cross flows on the wire responsible for fiber misalignment may have strong...