Sustainable and recyclable super engineering thermoplastic from biorenewable monomer

Environmental and health concerns force the search for sustainable super engineering plastics (SEPs) that utilise bio-derived cyclic monomers, e.g. isosorbide instead of restricted petrochemicals. However, previously reported bio-derived thermosets or thermoplastics rarely offer thermal/mechanical properties, scalability, or recycling that match those of petrochemical SEPs. Here we use a phase transfer catalyst to synthesise an isosorbide-based polymer with a high molecular weight >100 kg mol−1, which is reproducible at a 1-kg-scale production. It is transparent and solvent/melt-processible for recycling, with a glass transition temperature of 212 °C, a tensile strength of 78 MPa, and a thermal expansion coefficient of 23.8 ppm K−1. Such a performance combination has not been reported before for bio-based thermoplastics, petrochemical SEPs, or thermosets. Interestingly, quantum chemical simulations show the alicyclic bicyclic ring structure of isosorbide imposes stronger geometric restraint to polymer chain than the aromatic group of bisphenol-A.11Ysciescopu

Adsorption of phenol on mesoporous carbon CMK-3: effect of textural properties

Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol, carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption, respectively

Improving the efficiency of homologous recombination by chemical and biological approaches in Yarrowia lipolytica.

Gene targeting is a challenge in Yarrowia lipolytica (Y. lipolytica) where non-homologous end-joining (NHEJ) is predominant over homologous recombination (HR). To improve the frequency and efficiency of HR in Y. lipolytica, the ku70 gene responsible for a double stand break (DSB) repair in the NHEJ pathway was disrupted, and the cell cycle was synchronized to the S-phase with hydroxyurea, respectively. Consequently, the HR frequency was over 46% with very short homology regions (50 bp): the pex10 gene was accurately deleted at a frequency of 60% and the β-carotene biosynthetic genes were integrated at the correct locus at an average frequency of 53%. For repeated use, the URA3 marker gene was also excised and deleted at a frequency of 100% by HR between the 100 bp homology regions flanking the URA3 gene. It was shown that appropriate combination of these chemical and biological approaches was very effective to promote HR and construct genetically modified Y. lipolytica strains for biotechnological applications

Pore Structure and Separation Properties of Thin Film Composite Forward Osmosis Membrane with Different Support Structures

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Efficiency of gene deletion.

<p>Cells treated or untreated with HU were transformed with a <i>pex10</i>-deletion cassette with 50 bp of homology arm to the <i>pex10</i> gene. The <i>pex10</i> deletion rates (%) are shown and the number of total transformants screened is included in parentheses. WT indicates the wild-type <i>Y</i>. <i>lipolytica</i> Po1f strain. The experiments were performed in duplicate.</p

Strains and plasmids used in this study.

<p>Strains and plasmids used in this study.</p

Efficiency of URA3 marker deletion by HR.

<p>For URA3 selection marker reuse, the strains integrated with deletion or integration cassette containing URA3 marker were grown overnight in the YPD liquid medium and then plated on the 5-FOA selection medium. The percentage of URA3 marker deletion is shown and the number of total colonies screened is included in parentheses. The experiments were performed in duplicate.</p

ESI-mass spectrum and representative expansion of β-carotene produced by the resulting β-carotene producing strain, crtI/YB/E.

<p>(A) ESI-mass spectrum of the wild-type <i>Y</i>. <i>lipolytica</i> strain. (B) ESI-mass spectrum of the resulting β–carotene producing strain (crtI/YB/E). All strains was cultivated for 6 days at 30°C in 50 mL of YPD medium containing 20 g/L glucose. The experiments were performed in duplicate, and the representative results are shown.</p

Engineering of β-carotene biosynthetic pathway.

<p>(A) A schematic representation of the β-carotene biosynthetic pathway in <i>Y</i>. <i>lipolytica</i>. Integrated genes include geranyl diphosphate synthase (<i>crtE</i>), phytoene synthase (<i>crtYB</i>) and carotene desaturase (<i>crtI</i>). (B) Scheme for the construction of the β-carotene producing strain and the efficiency of targeted gene integration. The <i>crtI</i>, <i>crtYB</i> and <i>crtE</i> genes, driven by their individual 4UAS1B promoters, were integrated into the <i>pox1</i>, <i>pox2</i> and <i>pox3</i> sites in the <i>ku70</i>-disrupted <i>Y</i>. <i>lipolytica</i> strain, respectively. Cells treated with HU were transformed with the gene replacement cassette with 50 bp of homology arm to the target gene. The gene targeting rate (%) is shown, and the numbers in parentheses represent the correct integrants/total transformants screened. The experiments were performed in duplicate. HMG-CoA, 3-hydroxy-3-methylgluratyl-coenzyme A; MVA, mevalonic acid; DMPAA, dimethylallyl pyrophosphate; IPP, isopentyl pyrophosphate; PP, pyrophosphate.</p