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Non-recyclable fiber rejects from paper mills, particularly those from recycled linerboard mills, contain high levels of structural carbohydrates but are currently landfilled, causing financial and environmental burdens. The aim of this study was to develop efficient and sustainable bioprocess to upcycle these rejects into polyhydroxybutyrate (PHB), a biodegradable alternative to degradation-resistant petroleum-based plastics. To achieve high yields of PHB per unit biomass, the specific objective of the study was to investigate various approaches to enhance the hydrolysis yields of fiber rejects to maximize sugar recovery and evaluate the fermentation performance of these sugars using Escherichia coli LSBJ. The investigated approaches included size reduction, surfactant addition, and a chemical-free hydrothermal pretreatment process. A two-step hydrothermal pretreatment, involving a hot water pretreatment (150 °C and 15% solid loading for 10 min) followed by three cycles of disk refining, was found to be highly effective and resulted in an 83% cellulose conversion during hydrolysis. The hydrolysate obtained from pretreated biomass normally requires a detoxification step to enhance fermentation efficiency. However, the hydrolysate obtained from the pretreated biomass contained minimal to no inhibitory compounds, as indicated by the efficient sugar fermentation and high PHB yields, which were comparable to those from fermenting raw biomass hydrolysate. The structural and thermal properties of the extracted PHB were analyzed using various techniques and consistent with standard PHB. [ABSTRACT FROM AUTHOR]

Rotary viscous couplings with interleaved, perforated plates and viscous fluids are used in automotive systems to transmit torque. During operation, viscous dissipation raises fluid temperature, lowers fluid viscosity and causes the torque transmitted to drop monotonically to unusable levels. Couplings designed with certain plate geometry exhibit a reversal of the torque trend with temperature, and transmit increasingly high torque even under continuous operation. Such couplings achieve torque amplification factors in excess of twenty, compared to earlier couplings. This torque amplification phenomenon has been utilized by industry without fully understanding the mechanisms involved. A comprehensive theory is proposed to explain the complex sequence of events that results in this 'anomalous,' but useful phenomenon. Mathematical models are developed for each interdependent process. A visual simulation tool is used to model the intricate dynamics inside the coupling. Results from the simulation model are compared with experimental findings. The various thermodynamic, hydrodynamic, structural and mechanical processes are delineated and tested with a combination of theoretical analysis, computational simulation and experimental observations. The proposed theory identifies, defines and explains the conditions necessary for initiating and sustaining the self-induced torque amplification. The hypotheses are validated by the reasonable agreement of the model with the test results.

Porous biomaterials such as paper and board have a complex structure that influences their mechanical, optical, and transport properties and thereby their performance during manufacturing and end uses. Reconstruction of the three-dimensional (3D) pore spaces in paper was obtained by X-ray computed tomography and used to study the structure and its impact on properties. A set of laboratory-made paper samples of varying freeness was prepared, and the 3D structures of the samples were visualized and characterized. Tomographic reconstruction images were processed using techniques such as anisotropic diffusion, minimum error thresholding, and isolated voxel removal to enhance image quality. The pore structures were analyzed to determine porosity, fiberpore interfacial surface area, geometric tortuosity, and pore size distributions (using a sphere growing algorithm). These properties were compared with experimental data and were found to be in good agreement. The results from 3D visualization and characterization were then compared with experimental data of various samples using conventional pore structure characterization techniques, such as mercury intrusion porosimetry. [ABSTRACT FROM AUTHOR]