In this study anaerobic toxicity assays were used to quantify the relative toxicity of resin acids to the total toxicity in bleached chemithermomechanical wastewater. Fiber toxicity was also compared to raw bleached chemithermomechanical wastewater toxicity. Resin acids were found to be toxic to anaerobic bacteria but were not found to be responsible for all the toxicity in the wastewater. Toxicity associated with the fiber is soluble in methanol. The bulk of the fiber which is not methanol soluble exhibits no toxicity. Transfer of information obtained from batch modified anaerobic toxicity assays to continuous anaerobic treatment systems was also evaluated. Modified anaerobic toxicity assay data was compared to continuous toxicity assays using an upflow anaerobic sludge bed reactor. The continuous reactor was relatively unaffected by acute or chronic exposure to resin acids at concentrations that invoked inhibition in bath tests. Inferences from these tests indicated that batch modified anaerobic toxicity assay results may be unreliable when applied to continuous systems. (Abstract shortened by UMI.)

Abstract not available.

Arborists use formulas to estimate the risk of failure in trees with decay. The study investigates the appropriateness of using formulas to determine the risk of tree failure. Two variables were examined, whether trees improve wood toughness in the vicinity of mechanical stress concentrations, and how well the formulas estimate the loss in moment of inertia due to decay. Red maple (Acer rubrum) callus wood toughness was consistently greater than for normal wood, but, in some cases, the formulas significantly underestimated the actual loss in moment of inertia. The improvement of callus wood toughness is not related to increases in mechanical stress on the tree, but instead seems to be related to callus cell anatomy.

No description available.

Direct liquefaction of wood with aqueous HI solution to a wood oil product under low severity conditions, atmospheric pressure and low temperature around 125°C, was investigated in two stages. The first stage involved batch reactor studies. The wood-HI liquefaction reaction is fast, nearly complete in as little as 20s when the initial aqueous phase concentration is 57 wt% HI or greater. Yield of the char-type residue, a major problem in other liquefaction processes, is completely eliminated provided the final aqueous phase concentration is 50 wt% HI or above. The performance of this process with wood is better than would be predicted from experiments on the liquefaction of wood components determined separately. / Removal of oxygen from polymeric wood components is accomplished with oxidation of I- to I2. The second stage tested a novel concept for closing the HI → I2 → HI loop, an electrochemical liquefaction reactor (ECLR) with liquefaction in the cathode cell where I2 is simultaneously reduced back to I- . Electrolysis of water at the anode generates O2 and the H+ required at the platinum cathode for HI regeneration. Without wood liquefaction, current efficiency for I2 reduction is 90--100% and I2 concentration can be maintained at about 0.1 M, which is about 10% of that without I2 reduction. / Preliminary ECLR tests in batch and batchwise-continuous modes demonstrated simultaneous wood liquefaction and electrochemical reduction of I2 in the presence of the viscous wood oil. Also the iodine content of the crude wood oil is thereby reduced by about 60%, where this limit is imposed by the strong physical association between I2 and various functional groups in the product. Generation of H2, the competitive reaction, can be avoided. / ECLR characteristics were determined from a continuous run in a sealed reactor at a steady aqueous phase concentration of 55 wt% HI with a cathode current density of 0.81 A/cm2 at a cell voltage of 6 V. Carbon base yields were 84.2% crude wood oil product, 4.9% methyl iodide from the lignin methoxy groups and no production of the char-type residue common to other biomass liquefaction processes. Of the I2 produced, 93% would be reduced to HI, the other 7% being I2 associated physically with the product. Of the H+ generated at the anode, about half is used for HI regeneration and half for electrochemical liquefaction reactions as reflected by the exceptionally high levels of hydrogen retention and oxygen removal of the wood oil relative to the wood, above 85% in both cases.

A catalyzed chemimechanical-anthraquinone pulping of black spruce wood was investigated in this study. The effect of liquor pH on anthraquinone performance, AQ and mass transfer limitations on chemimechanical pulp properties and the effects of AQ, liquor pH and sulphite concentration on pulping kinetic were studied. / It was observed that AQ was not an effective redox catalyst when added to the sulphite liquor at pH 4, but it was very effective at pH 7 and higher. When chemical treatment of chemimechanical pulping was done with the presence of AQ, the sulphur content of pulp was reduced due to preferential reaction of AQ with wood components. AQ, as a pulping agent, is much effective in increasing the delignification rate and at the same time protecting the degradation of carbohydrates. / Pulps produced from wood wafers with cooking liquor at pH 7 containing 0.1% of AQ on oven dry wood, exhibited the following improved properties when compared with those prepared without addition of AQ: increased pulping rate, higher pulp yield and carbohydrates yield at the same level of residual lignin in pulp, and in addition, the strength properties such as breaking length and burst strength improved by 15% even with a minimum AQ charge (0.05% and 0.01%). / With regular wood chips, the penetration of sulphite seems to be superior to that of AQ. It was observed that AQ was not uniformly distributed in the impregnated wood chips even when the compression ratio was increased from 3.5:1 to 5:1. The penetration of AQ into wood chips remains to be a major factor affecting the pulping rate and pulp properties (strength and brightness) in chemimechanical-AQ pulping. / The rate of delignification in the initial phase of both sulphite and sulphite-AQ cooking at pH 7 shows the second order reaction in the remaining lignin. The order with respect to sulphite concentration for sulphite and sulphite-AQ cooking were estimated to be 0.24 and 0.31, respectively. The activation energies of delignification of the initial phase in sulphite and sulphite-AQ pulping were 90.2 and 97.5 kJ/mole which was valid up to 30% lignin removal within the temperature range of 160°C and 175°C. AQ as a pulping additive introduced to the sulphite liquor increased the rate of delignification 1.5 times in the initial phase of delignification during the sulphite cooking process. / At initial pH of sulphite liquor ranging from 7 to 10, the rate of delignification in the initial phase during sulphite and sulphite-AQ cooking appears to be a second order reaction in the remaining lignin. The reaction orders with respect to sulphite concentration increases when the initial pH is below 8 and decreases when the initial pH is above 8 for both sulphite and sulphite-AQ cooking. The raw of delignificafion is dependent on the initial pH of cooking liquor and the addition of AQ.

In Clostridium acetobutylicum the three enzymes thiolase, CoA-transferase, and acetoacetate decarboxylase serve to catalyze the formation of acetone from acetyl-CoA. This process is unique to butyric-acid clostridia and has long-term industrial significance. These three enzymes are known to he induced at the onset of solvent production. Both the acetoacetate decarboxylase and CoA-transferase activities are often spontaneously lost in degenerative mutants. To further investigate the regulatory mechanisms governing the expression of these enzymes, the genes encoding each of the three enzymes were cloned and expressed in Escherichia coli. The CoA-transferase is an $\alpha\sb2$,$\beta\sb2$ heterotetramer of 23 and 26 kDa subunits. Cloning revealed the enzyme is encoded by two genes (actA and actB). Genes for both subunits of the CoA-transferase were located in an operon arrangement. DNA sequence analysis suggests that these genes are co-transcribed as part of a larger operon from an upstream promoter. The adc gene, encoding the acetoacetate decarboxylase, was cloned and physically mapped downstream from the CoA-transferase genes. However, it is not part of the actAB operon, being oriented in the opposite direction. DNA sequencing analysis demonstrates transcription of the adc as a monocistronic operon. The 65 bp intergenic region between the C-termini of the adc and actB genes is characterized by a novel stem-loop structure which appears capable of rho-independent transcription termination function in both directions in C. acetobutylticum. The cloned adc gene was successfully reintroduced into a C. acetobutylicum adc$\sp-$ mutant, resulting in wild-type regulation and expression of the gene. The gene encoding the thiolase (thl) was also cloned, although it is not located near the other acetone production genes. The cloned thiolase is transcribed from its own promoter. No other thiolase genes were identified. A profound bias for adenine or thymidine in the third ("wobble") position of each codon was demonstrated in all four genes sequenced. Despite preferential usage of codons rarely used in E. coli, the transcription of the genes, assembly of subunits, and high levels of enzyme activity indicate the genes were well expressed in E. coli.

Effects of superheated steam drying were determined for surface properties and pore structure of paper, properties which are important in the end use of paper. Two furnishes were investigated, thermomechanical pulp (TMP) and a TMP/kraft pulp blend. Drying of handsheets under matched conditions in air was used as the basis of comparison. / TMP paper dried in superheated steam has a slightly higher surface roughness, by about 0.5 $ mu$m at a roughness around 8 $ mu$m. This difference decreases with drying fluid temperature. It is also reduced by about half after a very light blade coating. Surface roughness of paper from 50/50 TMP/kraft blend is unaffected. / Superheated steam drying reduces substantially the linting propensity of TMP paper, by about 30%-60% depending on the criteria used. Improved lignin softening by higher web temperature from the beginning of drying in superheated steam drying is believed an important mechanism in improving bonding of surface fines and short fibre fragments. / The Z-direction bond strength of TMP paper after surface treatment with water is about 20% higher for sheets dried in steam. Time for water absorption is 100%-150% longer for superheated steam dried TMP paper and contact angle of water is also substantially increased. / Superheated steam drying substantially reduces the volume of micropores of diameter 0.2-0.6 $ mu$m while having no significant effect on larger pores. Thus superheated steam drying affects only the pore structure of the micronetwork. The decrease of micropore volume in superheated steam drying is associated with an increase of Z-direction bond strength and a decrease of light scattering coefficient.

The fundamental objectives of this research is to produce and study magnetically loaded fibers and magnetic paper. The lumen-loading of commercially available ferrimagnetic (Fe$ sb3$O$ sb4$, $ gamma$-Fe$ sb2$O$ sb3$) and ferromagnetic (CrO$ sb2$) pigments was first performed as a "physical" approach to prepare magnetic paper. Our experiments resulted in the determination of the "kraft pulp/$ gamma$-Fe$ sb2$O$ sb3$ pigment" composite as an optimal combination of optical, mechanical and magnetic properties. / We have also developed a "chemical" process for the preparation of magnetic fibers which consists of using a cellulosic substrate with ion-exchange properties for Fe(II), i.e. Na-carboxymethylcellulose, as a host matrix for the growth of very small iron oxide particles. The in situ oxidation reaction of Fe(OH)$ sb2$ in the fiber cell walls yielded to superparamagnetic ferrite particles of about 100 A. / Because magnetism is a value added property for paper, our specialty fibers allow exploration of new concepts in papermaking (e.g. fiber orientation during paper formation), information storage, paper handling in copiers, magnetographic printing, etc.

A new experimental apparatus for high intensity through drying of paper was constructed and commissioned. The principal direct measurements with this facility are the air flow rate, and on-line measurements from beginning to end of the drying of the air temperature and pressure above and below the sheet, the sheet surface temperature on the flow inlet side and the local moisture content of a 2.5 mm diameter spot of the sheet. The equipment, constructed for the use of either air or superheated steam as the drying fluid, was commissioned with air as the drying medium. This facility was tested using three levels of drying air temperature, 90$ sp circ$, 200$ sp circ$, and 300$ sp circ$C, for through-flow rates up to those for which pressure drop across the sheet did not exceed 40 kPa. Papers from kraft, TMP and blended furnishes of grammage between 44 and 100 g/m$ sp2$, were dried from a range of initial moisture contents. / Sheet moisture content was measured on-line with a custom made, 3-wavelength transmission-type infra-red moisture sensor with optical fibre leads permitting installation inside the dryer. / For the kraft and TMP papers for which satisfactory moisture sensor calibrations were obtained, the moisture content-time drying history curves were processed to yield drying rate curves with the instantaneous drying rate as a function of local sheet moisture content. (Abstract shortened by UMI.)