Penetration Indices of Hardwoods: A Quantitative Approach to Define Treatability

Fluid accessibility of various structural components of 15 hardwoods belonging to different treatability classes was studied by using water-soluble and organic solvent stains. Penetration was found to vary even among the species categorized under the same treatability class indicating large-scale variation within the existing treatability classes. A quantitative estimation of this behavior was obtained in the form of a penetration index. This approach indicates that treatability class needs a change for 5 of the 15 species studied

Treatability and Flow Path Studies in Bamboo Part I. Dendrocalamus Strictus Nees.

Bamboo is one of the strongest structural materials used in rural areas of developing countries. Because of its low durability, it often fails prematurely due to fungal, borer, and termite attack. Because of anatomical differences from both hardwoods and softwoods, difficulties in treatment have been encounterd and early failures in preservative treated bamboo often observed. The most important structures for flow of fluids are the vascular bundles. The vascular bundles occurring in the inner zone of the bamboo culm treat better than the vascular bundles at the periphery.Microscopic studies on the distribution of chemicals in Dendrocalamus strictus Nees. indicated that creosote: fuel oil penetrated more uniformly than water-soluble or organic solvent stains. The degree of penetration decreased with the increasing distance of other cells such as fibers and parenchyma tissues from the conducting vessels. At the microscopic level, treatability behavior improved from outer to inner zones along the wall thickness as well as from basal internodes to top internodes

Pressure Impregnation of Hardwoods: Treatment Schedules For Easy-To-Treat Indian Hardwoods

On the basis of penetration pattern of inorganic chemicals in the wood microstructure, penetration indices for different wood species were developed. Pressure treatment schedules have been suggested on the basis of penetration index and gross absorptions obtained with CCA salts in treatability class 'a' and 'b' hardwoods. Mango and kadam earlier placed under the 'a' treatability class have been transferred to the 'b' treatability class because of poor penetration of the fibers in these species. Similarly, white bombwe earlier classified under class 'b' has been shifted to class 'a' because of its high penetration index

Gyroid-Forming Diblock Copolymers Confined in Cylindrical Geometry: A Case of Extreme Makeover for Domain Morphology

The self-assembly of gyroid-forming diblock copolymers confined in cylindrical geometry is studied using a combination of computer simulations and experiments. The simulations, based on a system qualitatively representative of poly(styrene-b-isoprene), are performed with cylindrical nanopores of different diameter (D) and surface selectivity. The effects of the pore size and surface selectivity on morphology are systematically investigated. Different morphological sequences are predicted for two gyroid-forming diblock copolymers. The experiments are carried out on two gyroid-forming poly(styrene-b-dimethylsiloxane) block copolymer samples confined in the core of continuous core−shell nanofibers of different diameters, which are obtained by a coaxial two-fluid electrospinning technique. The internal microphase-separated morphologies of these fibers are investigated by transmission electron microscopy (TEM). Both simulations and experiments demonstrate that a rich variety of structures spontaneously form for the gyroid-forming diblock copolymers, depending on the conditions of cylindrical confinement. Many of these confinement-induced structures are quite different from those of cylinder-forming or lamella-forming block copolymers. Simulations further show that these structures depend sensitively on the block copolymer composition, surface selectivity, and the ratio D/L0 where L0 is the period of the equilibrium gyroid phase. While the simulation and experimental systems are representative of different chemistries, the morphological predictions of simulations are qualitatively consistent with the experimental observations.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract DAAD-19-02-D-0002)United States. Army Research Offic

Influence of Permeability on Pulping Behavior of Tropical Indian Hardwoods

In this paper, an attempt has been made to correlate pulping of six tropical Indian hardwoods with their permeability and penetration behavior.A poor correlation existed between pulping suitability indices and directional permeability. Pulping suitability indices were found to be poorly correlated even with the composite permeability of wood, indicated by loading of cooking chemicals into wood under pressure. Composite permeability of wood was found to have a good correlation with pulp yield. High composite permeability, an index of good penetration of the cells, always resulted in lower yield losses, e.g., in udal and kokko. A medium permeability resulted in medium yield (maharukh). A poor composite permeability resulting from poor penetration of the cells, despite high gas permeability in some cases (chilauni, eucalyptus, toon) resulted in higher carbohydrate losses

Influence of Permeability on Pulping Behavior of Tropical Indian Hardwoods

In this paper, an attempt has been made to correlate pulping of six tropical Indian hardwoods with their permeability and penetration behavior.A poor correlation existed between pulping suitability indices and directional permeability. Pulping suitability indices were found to be poorly correlated even with the composite permeability of wood, indicated by loading of cooking chemicals into wood under pressure. Composite permeability of wood was found to have a good correlation with pulp yield. High composite permeability, an index of good penetration of the cells, always resulted in lower yield losses, e.g., in udal and kokko. A medium permeability resulted in medium yield (maharukh). A poor composite permeability resulting from poor penetration of the cells, despite high gas permeability in some cases (chilauni, eucalyptus, toon) resulted in higher carbohydrate losses

GEOGRAPHICAL DISTRIBUTIONAL LIST OF ICHTHYOFAUNA OF THE GARHWAL HIMALAYA INDIA WITH SOME NEW RECORDS

Volume: 84Start Page: 126End Page: 13