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Metabolic engineering of Escherichia coli for direct production of 1,4-butanediol
Yim, Harry,Haselbeck, Robert,Niu, Wei,Pujol-Baxley, Catherine,Burgard, Anthony,Boldt, Jeff,Khandurina, Julia,Trawick, John D,Osterhout, Robin E,Stephen, Rosary,Estadilla, Jazell,Teisan, Sy,Schreyer, H Nature Publishing Group, a division of Macmillan P 2011 Nature chemical biology Vol.7 No.7
1,4-Butanediol (BDO) is an important commodity chemical used to manufacture over 2.5 million tons annually of valuable polymers, and it is currently produced exclusively through feedstocks derived from oil and natural gas. Herein we report what are to our knowledge the first direct biocatalytic routes to BDO from renewable carbohydrate feedstocks, leading to a strain of Escherichia coli capable of producing 18 g l<SUP>??1</SUP> of this highly reduced, non-natural chemical. A pathway-identification algorithm elucidated multiple pathways for the biosynthesis of BDO from common metabolic intermediates. Guided by a genome-scale metabolic model, we engineered the E. coli host to enhance anaerobic operation of the oxidative tricarboxylic acid cycle, thereby generating reducing power to drive the BDO pathway. The organism produced BDO from glucose, xylose, sucrose and biomass-derived mixed sugar streams. This work demonstrates a systems-based metabolic engineering approach to strain design and development that can enable new bioprocesses for commodity chemicals that are not naturally produced by living cells.
High polarity analytes in food - enrofloxacin and sulfadiazine in bovine tissue (CCQM-K141)
Windust, Anthony,McRae, Garnet,Meija, Juris,Mester, Zoltá,n,Melanson, Jeremy E,Croft, Meg,Johnston, Lesley,Murby, John,Rego, Eliane C P do,Violante, Fernando G M,Fernandes, Jane L N,Wollinger, W BUREAU INTERNATIONAL DES POIDS ET MESURES 2019 METROLOGIA -BERLIN- Vol.56 No.-
<P></P> <P>Within the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantitè de Matiére (CCQM), key comparison CCQM-K141 and associated pilot study CCQM-P178 were coordinated by the National Research Council Canada (NRC). This comparison was a Track A key comparison that formed part of the OAWG 10-year strategic plan. The comparison demonstrated capabilities for measuring high-polarity analytes in a high-fat and high-protein matrix. The measurand chosen as the model system was enrofloxacin and sulfadiazine in bovine tissue. Thirteen National Metrology Institutes or Designated Institutes participated in the CCQM-K141, while two National Metrology Institutes participated in CCQM-P178.</P> <P>The bovine muscle tissue study material was derived from a single live animal that was administered with chemical based pharmaceutical agents prior to processing. Therefore, the study material was naturally incurred, providing a true test of extraction procedures relative to more commonly encountered spiked materials. NRC confirmed excellent homogeneity and stability of the material prior to shipping. Three 10 g bottles of freeze dried powdered muscle tissue were supplied. NRC also provided isotopically labelled solutions of the two measurands, <SUP>13</SUP>C<SUB>6</SUB>-sulfadiazine and enrofloxacin-d<SUB>5</SUB> (HI Salt), to those interested in using isotope dilution mass spectrometry (IDMS) methodologies. Procurement and purity assignment with appropriate metrological traceability of native calibrants were the responsibility of individual participants. The study required extraction, clean-up, analytical separation, and selective detection of the analytes.</P> <P>The level of agreement was reasonable given the measurands and matrix were new for most laboratories. The KCRV values and their uncertainties at the 95% confidence level of 57.81 ± 2.57 μg/kg for enrofloxacin and 2285 ± 68 μg/kg for sulfadiazine were calculated using the DSL means. While one participant's value was voluntarily excluded from the KCRV calculations for enrofloxacin, all other participants demonstrated equivalence for both measurands.</P> <P>Significant effort was undertaken post-study to identify the major sources of variability between results. In particular, the various extraction conditions used by participants were investigated thoroughly. While there appeared to be a correlation between highly acidic conditions and higher recovery, this was not definitive and could not be confirmed. The form of standards employed (i.e. free base vs salts) and potential differential solubility between forms was also a suspected source of variability. Biases could also have been introduced with the choice of solvents used for standard preparation, with some solvents better able to minimize adsorption of the analytes to glass surfaces.</P> <P>KEY WORDS FOR SEARCH</P> <P>enrofloxacin, sulfadiazine, bovine tissue, incurred, key comparison</P> <P></P> <H2>Main text</H2> <P> To reach the main text of this paper, click on <A HREF='https://www.bipm.org/utils/common/pdf/final_reports/QM/K141/CCQM-K141.pdf'>Final Report</A>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <A HREF='http://kcdb.bipm.org/'>kcdb.bipm.org/</A>.</P> <P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>
Nam, Sooji,Jang, Jaeyoung,Anthony, John. E.,Park, Jong-Jin,Park, Chan Eon,Kim, Kinam American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.6
<P>Solution-processable small-molecule organic semiconductors have recently attracted significant attention for use as the active channel layers in organic field-effect transistors due to their good intrinsic charge carrier mobility and easy processability. Dip-coating is a good method for optimizing the film morphology and molecular ordering of the small-molecular semiconductors because the drying speed can be quantitatively controlled at the air–solution–substrate contact line. Here, we report the preparation of highly crystalline triethylsilylethynyl–anthradithiophene (TES-ADT) crystal arrays that exhibit an excellent field-effect mobility (up to 1.8 cm<SUP>2</SUP>/(V s)) via an optimized one-step dip-coating process. High-quality TES-ADT crystals were grown without solvent vapor annealing postprocessing steps, which were previously thought to be essential for improving the morphology, crystallinity, and electrical characteristics of TES-ADT thin films. An interesting correlation between the optimal pull-out rate and the self-assembly tendencies of some soluble acene semiconductors was observed, and the origin of the correlation was investigated. Our work demonstrates an alternative simple approach to achieving highly crystalline TES-ADT thin films, and further proposes a prospective method for optimizing the formation of thin films via the molecular self-assembly of soluble acenes.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-6/am303192b/production/images/medium/am-2012-03192b_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am303192b'>ACS Electronic Supporting Info</A></P>
Lee, Wi Hyoung,Kwak, Donghoon,Anthony, John E.,Lee, Hwa Sung,Choi, Hyun Ho,Kim, Do Hwan,Lee, Seung Goo,Cho, Kilwon WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.2
<P><B>Abstract</B></P><P>The phase‐separation characteristics of spin‐cast difluorinated‐triethylsilylethynyl anthradithiophene (F‐TESADT)/poly(methyl methacrylate) (PMMA) blends are investigated with the aim of fabricating transistors with a high field‐effect mobility and stability. It is found that the presence of PMMA in the F‐TESADT/PMMA blends prevents dewetting of F‐TESADT from the substrate and provides a platform for F‐TESADT molecules to segregate and crystallize at the air–film interface. By controlling the solvent evaporation rate of the spin‐cast blend solution, it is possible to regulate the phase separation of the two components, which in turn determines the structural development of the F‐TESADT crystals on PMMA. At a low solvent evaporation rate, a bilayer structure consisting of highly ordered F‐TESAT crystals on the top and low‐trap PMMA dielectric on the bottom can be fabricated by a one‐step spin‐casting process. The use of F‐TESADT/PMMA blend films in bottom gate transistors produces much higher field‐effect mobilities and greater stability than homo F‐TESADT films because the phase‐separated interface provides an efficient pathway for charge transport.</P>
Kim, Yong‐,Hoon,Yoo, Byungwook,Anthony, John E.,Park, Sung Kyu WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.4
<P><B>Ink‐jet printed small‐molecule organic single‐crystal transistors</B> are realized by using selective surface energy modification, precise control of volume density of ink droplets on spatially patterned areas, and a co‐solvent system to control solvent evaporation properties. The single‐crystal formation in bottom‐contact‐structured transistors via direct printing is expected to permit high‐density array fabrication in large‐area electronics.</P>
Kim, Se Hyun,Jang, Mi,Yang, Hoichang,Anthony, John E.,Park, Chan Eon WILEY‐VCH Verlag 2011 Advanced Functional Materials Vol.21 No.12
<P><B>Abstract</B></P><P>A chemically coupled polymer layer is introduced onto inorganic oxide dielectrics from a dilute chlorosilane‐terminated polystyrene (PS) solution. As a result of this surface modification, hydrophilic‐oxide dielectrics gain hydrophobic, physicochemically stable properties. On such PS‐coupled SiO<SUB>2</SUB> or AlO<SUB><I>x</I></SUB> dielectrics, various vacuum‐ and solution‐processable organic semiconductors can develop highly ordered crystalline structures that provide higher field‐effect mobilities (<I>μ</I><SUB>FET</SUB>s) than other surface‐modified systems, and negligible hysteresis in organic field‐effect transistors (OFETs). In particular, the use of PS‐coupled AlO<SUB><I>x</I></SUB> nanodielectrics enables a solution‐processable triethylsilylethynyl anthradithiophene OFET to operate with <I>μ</I><SUB>FET</SUB> ∼ 1.26 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> at a gate voltage below –1 V. In addition, a complementary metal‐oxide semiconductor‐like organic inverter with a high voltage gain of approximately 32 was successfully fabricated on a PS‐coupled SiO<SUB>2</SUB> dielectric.</P>
Jang, Jaeyoung,Park, Jaesung,Nam, Sooji,Anthony, John E,Kim, Youngsoo,Kim, Keun Soo,Kim, Kwang S,Hong, Byung Hee,Park, Chan Eon RSC Pub 2013 Nanoscale Vol.5 No.22
<P>Graphene has shown great potential as an electrode material for organic electronic devices such as organic field-effect transistors (FETs) because of its high conductivity, thinness, and good compatibility with organic semiconductor materials. To achieve high performance in graphene-based organic FETs, favorable molecular orientation and good crystallinity of organic semiconductors on graphene are desired. This strongly depends on the surface properties of graphene. Here, we investigate the effects of polymer residues that remain on graphene source/drain electrodes after the transfer/patterning processes on the self-organizing properties and field-effect characteristics of the overlying solution-processed triethylsilylethynyl-anthradithiophene (TES-ADT). A solvent-assisted polymer residue removal process was introduced to effectively remove residues or impurities on the graphene surface. Unlike vacuum-deposited small molecules, TES-ADT displayed a standing-up molecular assembly, which facilitates lateral charge transport, on both the residue-removed clean graphene and as-transferred graphene with polymer residues. However, TES-ADT films grown on the cleaned graphene showed a higher crystallinity and larger grain size than those on the as-transferred graphene. The resulting TES-ADT FETs using cleaned graphene source/drain electrodes therefore exhibited a superior device performance compared to devices using as-transferred graphene electrodes, with mobilities as high as 1.38 cm(2) V(-1) s(-1).</P>
Photo‐Curable Polymer Blend Dielectrics for Advancing Organic Field‐Effect Transistor Applications
Kim, Se Hyun,Hong, Kipyo,Jang, Mi,Jang, Jaeyoung,Anthony, John E.,Yang, Hoichang,Park, Chan Eon WILEY‐VCH Verlag 2010 Advanced Materials Vol.22 No.43
<P><B>A solution method of photo‐curable and ‐patternable polymer gate dielectrics</B> was introduced by using blend solutions of poly(4‐dimethylsilyl styrene) (PDMSS) and poly(melamine‐co‐formaldehyde) acrylate (PMFA). The fabrication was optimized to produce a smooth hydrophobic gate dielectric with good insulating and solvent‐resistant properties. On the optimized PDMSS/PMFA blend gate dielectric, pentacene could grow into highly ordered structure, showing high electric performances for the resulting OFETs, as well as PTCDI‐C13 and TES‐ADT.</P>