In an attempt to develop a method by which the chemical components of whole wood samples could be separated on a quantitative basis, the reactions of gaseous dinitrogen pentoxide with model substances and with acetone-extracted wood have been studied. The crystalline compounds D-mannitol, benzoic acid and D,L-tartaric acid were smoothly nitrated by exposure to an excess of the pentoxide at 0 ± 2° C. and the crystalline products D-mannitol hexanitrate, D,L-tartaric acid dinitrate and m-nitrobenzoic acid were recovered directly in quantitative yield. Good yields of the crystalline although somewhat less pure nitrates of D,L-mandelic acid, β-methyl-D-glucopyranoside and D-sorbitol were obtained in similar nitrations. D-Mannose, D-fructose, dulcitol, sucrose, maltose, lactose, cellobiose, vanillic acid, salicylic acid and vanillin gave poor yields of syrupy nitrated products. A beechwood xylan and holocellulose and lignin of western red cedar, isolated by conventional technics, were nitrated by the gaseous pentoxide method in yields and nitrogen contents comparable to those reported for other nitration methods. The xylan and holocellulose nitrates were incompletely soluble in acetone and the solubility of the nitrated lignin varied with the time of nitration. Optimum conditions were established for the nitration of acetone-extracted western red cedar heartwood. The weight ratio of nitrated wood : wood was closely reproducible and exceeded previously reported values; total nitrogen and ester nitrogen contents of the nitrated wood were reproducible within, the experimental error of the determinations. The nitration reaction was not entirely quantitative since an average of 2.3% methoxyl was lost from the wood and the weight increase calculated from the total nitrogen content was, on the average, 3% lower than the observed value. Successive extraction with anhydrous acetone and methanol applied alternately, dissolved up to thirty-five percent of the nitro-wood and indicated that the nitration-solvent extraction technic should have value as a tool in the study of wood chemistry. / Science, Faculty of / Chemistry, Department of / Graduate

Spiral grain in timber may cause severe twisting of lumber and plywood. In the primary forest products industries the presence of spiral grain in the tree results in cross-grained products. Cross grain affects the strength properties of lumber to a marked degree. Thus a grain deviation of 1 In 25 (2°18') results in decreased tensile strength whereas a slope of 1 in 10 (5°43') will reduce compression strength. Spiral grain is a condition well known to the wood technologist and the silviculturalist. Until recently it was considered the exception rather than the rule. From recently published papers, however, and from unpublished data available to the author, strong evidence has been produced to show that spiral grain is the normal growth pattern in trees. This thesis is designed to investigate the spiral pattern of second-growth Douglas fir and western hemlock. Accordingly three sites were chosen: a good, a medium and a low site in a typical British Columbia coastal forest of second growth. Two crown classes for each species were sampled from each site and three trees in each crown class for each species were felled and their spiral patterns investigated. A general trend of spirality was established, the twist being initially left (at first), decreasing to the left and becoming right with increasing age. This pattern holds good for both species. The effect of site on spiral development was established as highly significant with both species. On high quality sites the chief factor influencing spiral development was found to be distance from the pith. On sites of lower quality, age from the pith was found to have the most significant influence on spiral development. / Forestry, Faculty of / Graduate

Two sets of data are analyzed in the thesis. The first set was derived from the long term deformations of 2 in x 6 in x 12 ft (40 mm x 140 mm x 3600 mm) joists of Douglas-Fir loaded under constant bending stress to levels lower than or equal to 3110 psi (21.44 MPa). The second set was derived from the long term deformations of 2 in x 6 in x 12 ft joists of Hemlock loaded under constant bending stress to levels of 3000 psi (20.68 MPa) and 4500 psi (31.0 2 MPa) . The analysis shows that the creep behaviour of structural size beams depends upon the material characteristics; specifically, material with a strength lower than 5000 psi (34.33 MPa) appeared to creep 1.5 times more than, material with a strength higher than that level, over a three month period. In addition, the test results support the assumption of a linear relationship between the creep deformation of a structural-size timber beam and applied stress. A method is presented to predict the creep behaviour of a structural-size specimen at discrete times over a three month period. The method consists of expressing the creep deformation, Δ[sub c], in terms of the elastic deformation, δ[sub e], or equivalently, the fractional creep (f = δ[sub c] / δ[sub e]) in terms of δ[sub e] or in terms of the modulus of elasticity. This work is limited to the stress levels investigated and to specific temperature (10°C< θ <30°C) and moisture content (8%<MC<12%) conditions. While this method could be employed in preliminary design procedures, it has been especially designed for more complex studies of the creep behaviour of structures including floor systems, trusses, etc... The advantage of the method is that in this kind, of analysis the modulus of elasticity of the individual components can be used. This thesis also presents a set of creep curves that cover a three year span. These creep curves show that the average total deformation of beams loaded to a stress level of 3110 psi (21.44 MPa), at this time, is approximately 1.6 times the elastic deformation. / Applied Science, Faculty of / Civil Engineering, Department of / Unknown

Present methods of determining design values for compression perpendicular to grain involves the testing of specimens of one specific geometry. The geometry of this test is very different from the geometries of bearing conditions occurring in practice. It was hypothesized that this test does not represent actual bearing conditions in practice and the object of this thesis was to find a more representative method of designing for compression perpendicular to grain. This thesis found the behaviour of wood in compression perpendicular to grain loading is strongly dependent on geometry in both the linear and nonlinear ranges of applied loading. A finite element analytical model, verified by testing, was used for the analysis. The analysis found the deflection is strongly dependent on the modulus of elasticity perpendicular to grain and nearly independent of other material properties. Also the capacity was found to be dependent on a characteristic material term and only weakly dependent on other material properties. A design method, one which includes an estimate of the deflection of the bearing plate, was developed from the results of this research. This proposed design method is valid for the capacities of the different geometries of bearing conditions occurring in practice. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The water potential concept and generalized Darcy's law for unsaturated flow were proposed as a basis for the study of the energy state and flow of water in wood at high moisture contents. A series of experiments was conducted to investigate wood properties that are crucial to the application of these theories. Much attention was devoted to the measurement of the moisture content-matric potential (M-Ψm) relationship by the porous plate methods. Both the boundary drainage and imbibition curves and the drainage curve starting from the green condition were determined. In addition, independent Ψm measurements were made in some of the specimens equilibrated on the porous plates using Wescor PT51-10 thermocouple psychrometers (TCP). The osmotic potential was then assumed to be negligible. Transient flow experiments were also conducted for determining the water conductivity (K) as a function of both M and Ψm, and the water diffusivity (D) as a function of M using an instantaneous profile method and the one-step method. The boundary drainage and imbibition curves for the longitudinal direction of flow were thus obtained. The saturated conductivity had to be measured separately. Western hemlock sapwood was used for all determinations which were made at a temperature of 21°C. The results of the porous plate tests confirmed the presence of a considerable hysteresis in the M-Ψm relationship at high moisture contents, with M at a given Ψm greater in drainage than in imbibition. The ink-bottle effect appears to be the primary cause of this phenomenon. Both types of drainage curves obtained showed a tendency to exhibit a plateau at intermediate M's and were found highly dependent on the initial moisture content. A fairly good agreement was found between the Ψm values imposed on the specimens on the porous plates and those measured by the TCP's for the Ψm range from -1 to -7 bars in drainage. These two types of data differed markedly at lower Ψm 's in drainage and in imbibition. However, the differences observed in imbibition were readily explainable and the results of the TCP tests clearly demonstrated the strong hysteretic behavior of the M-Ψm relationship in the wet state. The reproducibility of the TCP method during the Ψm measurements in wood was rather poor. The K-M, K- Ψm, and D-M curves obtained by the two transient methods used were very similar in shape. The K(M) function exhibited a considerable hysteresis with K at a given M greater in imbibition than in drainage. A change in K of several orders of magnitude was recorded near full saturation. The K(Ψm) and D(M) functions displayed only a partial hysteresis. Disproportionality between flux and gradient was observed in imbibition above 75% M. The non-uniqueness of the M- Ψm relationship with respect to the state of flow was apparently the main cause of this anomaly. / Land and Food Systems, Faculty of / Graduate

Bibliography: leaves 154-160. / In light of the dependence of the majority of rural South Africans on fuelwood as their major energy source and the rapid diminution of this resource, the aims of this thesis were to investigate the design of a fuel-efficient woodburning stove, appropriate to and acceptable in the underdeveloped areas of South Africa, and to assess the potential for woodstoves in the mitigation of the fuelwood crisis and deforestation in these areas. This involved a review of international experience in stove development and dissemination from which the relative successes of differing designs and dissemination strategies were assessed. Stove design guidelines were also gleaned from the literature survey. Information on existing fuelwood usage and cooking patterns in the target areas was collected and incorporated in the design criteria for two prototypes. It was decided to develop light-weight metal prototypes that could be manufactured in minimally equipped rural workshops, since user constructed heavy-mass mud stoves were deemed to be inappropriate for warm climates and relatively short cooking times, and their dissemination was inhibited by hidden difficulties and costs. The two prototypes developed included a chimneyless bucket type (Onepot) which supported one, either three legged cast iron or flat bottomed aluminium, pot of maximum diameter 280 mm, and a chimney stove (Twopot) accommodating two cooking pots and one hot water container. Both stoves were lined on the inside with a 2 cm thick layer of vermiculite/firebrick mixture. These stoves underwent testing in a specifically equipped laboratory, to determine their efficiency versus power performance and to identify the main heat losses. At a nominal power input of 3 kW, the Onepot had an efficiency of 55% and at a nominal power input of 5 kW, the Twopot had an efficiency of 40%. The power range of both stoves was limiting, as the efficiency fell sharply with increasing power input. In the Twopot this was probably due to the under sizing of the grate area, as the combustion intensities on the grate were much less than those used in the design (37,5 W/ cm2 compared to 50 W/ cm2 ). A number of each prototype underwent field trials for six months in two rural villages in KwaZulu namely Biyela and Scheepersdal. In the assessment open discussions and interviews were held. It was found that the Onepot stoves were not used regularly because of their limitation of heating only one pot at a time. The Twopot stoves were more popular, however the main areas that still required attention were durability, incorporation of an oven and aesthetics of appearance. A theoretical model was developed and, for the Onepot stove, predicted that increasing insulation thickness would not result in significant increase in heat transferred to the pot in the burning rate ranges investigated. In conclusion, recommendations were made for re-design of the Twopot stove, mainly to increase durability and acceptability. It was felt that more work on combustion characteristics in the firebox was needed for better modelling of the stove. However, it was deemed that the greatest challenges for attaining the broader goals of this project lay with proving fuelwood savings in the field and devising successful dissemination strategies.

No description available.

Lightweight wood construction is one of the most common forms of residential construction in the United States. Unprotected lightweight wood structural members are extremely sensitive to elevated temperatures often experienced in fire conditions. Residential fires are a commonly occurring incident across the globe and consequently make up a large percentage of residential property loss and damage. In the United States, building code provisions limit lightweight construction to particular building types. These building codes prescribe protected lightweight wood assemblies in building types for which they are allowed. Although many components of lightweight wood buildings are required to be protected in some form, there are still many parts of the building that are not necessarily required to be protected, especially in private residential structures. A fire may start in an area of a building that is protected, but may propagate into areas that are not. This leaves portions of the unprotected structure vulnerable to rapid fire damage. Lightweight wood members can quickly lose load resistance due to a loss of cross-section as a result of charring. Analytical models currently exist and are generally accepted for heavy timber elements, but the applications of these models do not extend to lightweight wood members. As a result, this thesis investigated the application of an analytical model to lightweight wood elements. In developing this model, the finite element method and finite difference models were used to investigate the phenomenon of wood char in fire conditions. Finite difference models were explored as an alternative to finite element models because finite difference formulations did not require specialty programs. Following the development of analytical char models, mechanics-based analyses were conducted to evaluate the performance of lightweight beams and columns exposed to fire conditions.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains ix, 106 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 75-76).

M.S. / Biochemistry / The white-rot basidiomycete Phanerochaete chrysosporium produces intracellular soluble and particulate ß-glucosidases and an extracellular ß-glucosidase. The extracellular enzyme is induced by cellulose but repressed in the presence of glucose. The molecular weight of this enzyme is 90,000. The K [subscript m] for -p-nitrophenyl-ß-glucoside is 1.6 x 10[superscript -4] M; the K [subscript 1] for glucose, a competitive inhibitor, is 5.0 x 10[superscript -4] M. The K [subscript m] for cellobiose is 5.3 x 10[superscript -4] M. The intracellular soluble enzyme is induced by cellobiose; this induction is prevented by cycloheximide. The presence of 300 mM glucose in the medium, however, had no effect on induction. The K [subscript m] for p-nitrophenyl- ß -glucoside is 1.1 x 10[superscript -4] M. The molecular weight of this enzyme is about 410,000. Both enzymes have an optimal temperature of 60°C and an E [subscript act] of 9.15 kcal/mole. The pH optima, however, were 7.0 and 5.5 for the intracellular and extracellular enzymes, respectively.