Muconic acid is a valuable platform chemical with potential applications in the production of polymers such as nylon and polyethylene terephthalate (PET). The conjugate base, muconate, has been previously biosynthesized in the bacterial host Escherichia coli. Likewise, previous significant pathway engineering lead to the first reported instance of rationally engineered production of muconic acid in the yeast Saccharomyces cerevisiae. To further increase muconic acid production in this host, a combined adaptive laboratory evolution (ALE) strategy and rational metabolic engineering is employed. To this end, a biosensor module that responds to the endogenous aromatic amino acid (AAA) as a surrogate for pathway flux is adapted. Following two rounds of ALE coupled with an anti-metabolite feeding strategy, the strains with improved AAA pathway flux is isolated. Next, it is demonstrated that this increased flux can be redirected into the composite muconic acid pathway with a threefold increase in the total titer of the composite pathway compared to our previously engineered strain. Finally, a truncation of the penta-functional ARO1 protein is complemented and overexpress an endogenous aromatic decarboxylase to establish a final strain capable of producing 0.5 g L muconic acid in shake flasks and 2.1 g L in a fed-batch bioreactor with a yield of 12.9 mg muconic acid/g glucose at the rate of 9.0 mg h . This value represents the highest titer of muconic acid reported to date in S. cerevisiae, in addition to the highest reported titer of a shikimate pathway derivative in this host.

The transverse friction coefficient of a yarn sliding on a surface is much more difficult to measure than its lengthwise coefficient. A method based on the transverse sliding of the yarn on the cylindrical balloon limiter of a two-for-one twister is proposed to measure this coefficient. A simple yarn ballooning apparatus based on a hollow spindle was built and tested. A top picture of the cylindrically constrained yarn balloon is taken and the final yarn angle is measured. This angle can be theoretically correlated to the other easily measured parameters of the simplified balloon and to the desired transverse friction coefficient. This method was experimentally verified and found to be both practical and highly accurate.

Pneumatic valves with unequal upstream and downstream ori ce sizes make the proportional control of ow easier. It also enables the load to respond faster and increases the energy ef ciency of the controlled system. A plate valve is the only type where this difference in ori ce sizes can be implemented in a straightforward manner. A four-way, rotary plate valve was designed, constructed and analysed. The advantages of control and energy ef ciency that result when this valve is used in a pneumatic system are studied. Experimental results for the case of this valve controlling a pneumatic vane motor con rm the theoretical predictions. NOTATIONA ori ce area m 2 C constant C d discharge coef cient C p speci c heat at constant pressure J kg¯C f function k ratio of speci c heats m m mass owrate (kg/s) P absolute pressure (Pa) Q power (watts) r radius (m) T absolute temperature (K ) V vane motor displaced volume m 3 w width (m) X valve displacement (m) a ratio of downstream to upstream ori ce areas b geometric parameter of the pneumatic motor m 3 DP pressure difference (Pa) Z ef ciency y angular displacement (rad) r speci c mass kg m 3 t torque (N m) o angular speed (rad/s)