Research on Special Support Technology of Gob-side Entry Retaining with Filling the Non-roadway Side in the Thin Coal Seam

By taking a certain mining area of No.2 coal seam in a coal mine as the research object, special support technology of gob-side entry retaining with filling the non-roadway side was researched. Based on the geologic features of this mining area, support method of gob-side entry retaining was proposed. The method replaced the dense wood prop with single prop, and cooperated intersection hinge roof. The support parameters were calculated, and time-space coordination between each support process was researched. The field measured data showed that this support method had a remarkable effect and strictly controlled the deformation of gob-side entry. This research formed a support system and mining system based on this condition. It has important reference meaning to safe and efficient mining coal resource with similar geologic condition.

Determination of some wood properties and response to weathering of Citrus limon (L.) Burm wood

The ability of Citrus limon (L.) Burm wood to be used for flooring applications was considered in this work. Selected wood properties were determined, and the response to weathering was tested. Janka hardness, density, screw withdrawal resistance, color, glossiness, and artificial weathering (144, 288, and 432 h) were determined. The wood from Citrus limon was shown to be a dense wood with air density around 830 kg/m3 and with a high Janka hardness of 138.0 N/mm2, 120.4 N/mm2, and 115.9 N/mm2 for cross, tangential, and radial sections, respectively. This opens good perspectives to this kind of wood being used for flooring. Statistical analysis showed that both Janka hardness and screw withdrawal resistance were significantly different between surfaces. Nevertheless, the homogeneity groups showed that the main differences were between the surfaces in the longitudinal direction when compared with the transverse direction. The wood is lighter than most common woods and it is mainly yellow. After weathering, the wood became darker, redder, and yellower. Glossiness decreased in the first hours of the weathering period.

Szecladia new genus, a late Permian conifer with multiveined leaves from South China

A conifer from the uppermost Permian with small, helically arranged leaves is described from the Guangxi Autonomous Region and Guizhou Province of South China as Szecladia multinervia, new genus and species. The material includes both impression specimens and the first anatomically preserved Paleozoic conifer fossils from China. Shoots are irregularly branched, with small, helically arranged, multiveined leaves. Stems display an endarch eustele with abundant, dense wood. Leaf traces diverge from the stele as a single bundle that divides several times in the cortex and at the base of the leaves, forming about seven or eight parallel veins in each leaf. Szecladia is the earliest known conifer with multiveined leaves and it represents a distinctive coniferous element of the uppermost Permian Cathaysian flora in South China. Szecladia further demonstrates that conifers with wood and leaf venation suggestive of the Podocarpaceae may have evolved by the end of the Paleozoic.

Lengua Festivals and Functional Substitutes

A Lengua war party is returning. None of its members were injured. Four Lenguas have taken scalps. The raid has been a success… or has it ? The four heroes are sleeping apart from the rest of the war party surrounded by a circle of fire fueled by red quebracho wood (a hard and dense wood from which tannic acid is extracted) which throws off flares of sparks in all directions when it burns. The heroes are sleeping in their “fortress of fire” because they are afraid of the - jangaoc, the ‘souls of the dead’ of the slain enemies. They fear that these ‘souls' are even now pursuing them. How will these men ever regain peace of mind and their - valhoc, their ‘innermost?’ The answer is one month away. Then the band will have a festival to purify the heroes and to reinstate them as “clean” members of the group again. Then the four will be free of fear once more.

THE INFLUENCE OF PENETRATION IN THE ALKALINE DELIGNIFICATION OF WOOD

The effect of various factors that might possibly influence the penetration of soda liquor into spruce wood has been examined. It was found that the rate of delignification was the same irrespective of the size of the sample, from a wood-meal of 0.005 mm. particle size up to a limiting chip thickness of about 10 mm. The density of the wood had no influence on the delignification other than that which would be expected from the higher original lignin content of the more dense wood. The presence of moisture in the chips was without result other than that of diluting the liquor, and the addition of wetting agents for facilitating the penetration rate was without significant effect.