“
“Recombinant Methylobacterium extorquens ATCC 55366 harboring phaC2 from Pseudomonas fluorescens GK13 (M. ex-phaC2) was capable of producing blends of
polyhydroxyalkanoates. By co-feeding methanol and 5-hexenoic acid (C6=), functionalized PHAs (4 <= chain length <= 6) containing C-C double bonds were created. Bioreactor studies revealed negative impacts of 5-hexenoic acid on biomass and PHA production by reducing overall yields. In contrast, there was a positive https://www.selleckchem.com/products/BKM-120.html relationship between 5-hexenoic acid supply and abundance of polymeric functional groups, i.e., molar portions of monomeric units bearing double bonds increased with increased 5-hexenoic acid supply. Correlation of C6= consumption to methanol addition resulted in
a model that allowed for on-line estimation of toxic co-substrate concentration. The functionalized PHAs were ductile and showed signs of side Nepicastat solubility dmso chain crosslinking, resulting in reduced degrees of crystallinity. Incorporation of 3-hydroxyhex-5-enoate and 3-hydroxyhexanoate into the polymeric chains produced desirable thermal properties with enhanced thermal stability and reduced melting temperatures (139-168 degrees C). Thermal degradation and melting temperatures obtained suggest a comfortable range for melt-processing of these polymers and allow for autoclaving as convenient sterilization process. Consequently, functionalized PHAs produced in this study are candidates for medical applications as part
of biocomposite materials. The use of methanol as main substrate for cultivation of recombinant M. extorquens offers the selleckchem possibility to reduce production costs and develop new process control strategies. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.”
“The rheological properties of high concentrated wood pulp cellulose 1-allyl-3-methy-limidazolium Chloride ([Amim]Cl) solutions were investigated by using steady shear and dynamic viscoelastic measurement in a large range of concentrations (1025 wt %). The measurement reveals that cellulose may slightly degrade at 110 degrees C in [Amim]Cl and the CoxMerz rule is valid for 10 wt % cellulose solution. All of the cellulose solutions showed a shear thinning behavior over the shear rate at temperature from 80 to 120 degrees C. The zero shear viscosity (?o) was obtained by using the simplified Cross model to fit experimental data. The ?o values were used for detailed viscosity-concentration and activation energy analysis. The exponent in the viscosity-concentration power law was found to be 3.63 at 80 degrees C, which is comparable with cellulose dissolved in other solvents, and to be 5.14 at 120 degrees C. The activation energy of the cellulose solution dropped from 70.41 to 30.54 kJ/mol with an increase of concentration from 10 to 25 wt %.