| 1. |
- Lee, Hyun Ju, et al.
(author)
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Multi-step enzymatic synthesis of 1,9-nonanedioic acid from a renewable fatty acid and its application for the enzymatic production of biopolyesters
- 2019
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In: Polymers. - : MDPI AG. - 2073-4360. ; 11:10
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Journal article (peer-reviewed)abstract
- 1,9-Nonanedioic acid is one of the valuable building blocks for producing polyesters and polyamides. Thereby, whole-cell biosynthesis of 1,9-nonanedioic acid from oleic acid has been investigated. A recombinant Corynebacterium glutamicum, expressing the alcohol/aldehyde dehydrogenases (ChnDE) of Acinetobacter sp. NCIMB 9871, was constructed and used for the production of 1,9-nonanedioic acid from 9-hydroxynonanoic acid, which had been produced from oleic acid. When 9-hydroxynonanoic acid was added to a concentration of 20 mM in the reaction medium, 1,9-nonanedioic acid was produced to 16 mM within 8 h by the recombinant C. glutamicum. The dicarboxylic acid was isolated via crystallization and then used for the production of biopolyester by a lipase. For instance, the polyesterification of 1,9-nonanedioic acid and 1,8-octanediol in diphenyl ether by the immobilized lipase B from Candida antarctica led to formation of the polymer product with the number-average molecular weight (Mn) of approximately 21,000. Thereby, this study will contribute to biological synthesis of long chain dicarboxylic acids and their application for the enzymatic production of long chain biopolyesters.
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| 2. |
- Park, Hyunjoo, et al.
(author)
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Colorimetric Detection of Furfural with Enhanced Visible Absorption of Furfural-DNPH in Basic Conditions
- 2024
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In: ACS Omega. - 2470-1343. ; 9:2, s. 2519-2527
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Journal article (peer-reviewed)abstract
- Furfural is an intermediary toxic aldehyde compound produced during heat-induced food processing and storage. Furfural is also formed by the degradation of cellulosic insulation in oil-immersed electric potential transformers, whose level is an important indicator of aging for replacement. In this study, we report a new means to detect the trace level of furfural in a colorimetric manner. Furfural is reacted with dinitrophenylhydrazine (DNPH) in acid solutions. The colorless furfural-DNPH compound turns orange-colored as the solution changes to basic. The delocalization of the π-electron in the DNPH-aldehyde derivatives at the basic condition causes the shift of the absorption peak from 318 to 470 nm, which renders the solution orange-colored. The color and absorbance are saturated in 20 min of incubation. There is high linearity between the absorbance and the concentration of furfural in the range of 0-0.2 mM, which enables the quantitative detection of furfural. The limit of detection is estimated to be as low as 1.76 μM for the absorbance analysis and 10 μM for the naked eyes. The colorimetric assay protocol is applicable to the detection of various aromatic aldehydes, which show strong π-electron delocalization and is not applicable to aliphatic aldehydes due to lack of delocalization. This simple assay can be conducted in typical 96-well microplates using a microplate reader, which provides a low-cost and high-throughput screening. Therefore, we believe that our method is potentially applicable for the quantitative detection of aromatic aldehydes in various samples from foods, electronic devices, and so on.
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| 3. |
- Arzoumanian, Doris, et al.
(author)
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Dust polarized emission observations of NGC 6334: BISTRO reveals the details of the complex but organized magnetic field structure of the high-mass star-forming hub-filament network
- 2021
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 647
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Journal article (peer-reviewed)abstract
- Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-The-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments. Results. The observations span 3 orders of magnitude in Stokes I and PI and 2 orders of magnitude in PF (from 0.2 to 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region ( 10 pc); however, at smaller scales (1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of-1.33 ± 0.23, which is 20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 â 1023 cm-2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. Conclusions. These observational results reveal for the first time the characteristics of the small-scale (down to 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.
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| 4. |
- Bornadel, Amin, et al.
(author)
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Optimization of a two-step process comprising lipase catalysis and thermal cyclizationimproves the efficiency of synthesis of six-membered cyclic carbonate from trimethylolpropane and dimethylcarbonate.
- 2013
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In: Biotechnology Progress. - : Wiley. - 1520-6033 .- 8756-7938. ; 29:1, s. 66-73
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Journal article (peer-reviewed)abstract
- Six-membered cyclic carbonates are potential monomers for phosgene and/or isocyanate free polycarbonates and polyurethanes via ring-opening polymerization. A two-step process for their synthesis comprising lipase-catalyzed transesterificationofa polyol, trimethylolpropane(TMP) with dimethylcarbonate(DMC)in a solvent-free system followed by thermal cyclization was optimized to improve process efficiency and selectivity. Using full factorial designed experiments and partial least squares (PLS) modeling for thereaction catalyzed by Novozym®435 (N435; immobilized Candida antarctica lipase B), the optimum conditions for obtaining either high proportion of mono-carbonated TMP and TMP-cyclic-carbonate (3 and 4), or di-carbonated TMP and monocarbonated TMP-cyclic-carbonate (5 and 6) were found. The PLS model predicted that the reactions using 15-20% (w/w) N435 at DMC:TMP molar ratio of 10-30 can reach about 65% total yield of 3 and 4 within 10 h, and 65-70% total yield of 5 and 6 within 32-37 h, respectively. High consistency between the predictedresults and empirical data was shown with 66.1% yield of 3 and 4 at 7 h and 67.4% yield of 5 and 6 at 35 h, using 18% (w/w) biocatalyst and DMC:TMPmolar ratio of20. Thermal cyclization of the product from 7 h reaction, at 110 °C in the presence of acetonitrile increased the overall yield of cyclic carbonate 4 from about 2% to more than 75%within 24 h.N435 was reused for 5 consecutive batches, 10 h each, to give 3+4 with a yield of about 65% in each run. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012.
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| 5. |
- Bornadel, Amin, et al.
(author)
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Six-membered cyclic carbonates from trimethylolpropane : Lipase-mediated synthesis in a flow reactor and in silico evaluation of the reaction
- 2017
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In: Biotechnology Progress. - : Wiley. - 8756-7938. ; 33:2, s. 375-382
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Journal article (peer-reviewed)abstract
- Six-membered cyclic carbonates with hydroxyl and methoxycarbonyloxy functional groups were prepared by transesterification of trimethylolpropane (TMP) with dimethylcarbonate (DMC) by solvent-free lipase-mediated flow reaction followed by thermal cyclization. The flow reaction efficiency was evaluated using different configurations of reactor consisting of packed beds of Novozym®435 (immobilized Candida antarctica lipase B—CalB—a.k.a. N435) and molecular sieves, flowrate, and biocatalyst loads. The mixed column of the biocatalyst and molecular sieves, allowing rapid and efficient removal of the by-product—methanol—was the most efficient setup. Higher conversion (81.6%) in the flow reaction compared to batch process (72%) was obtained using same amount of N435 (20% (w/w) N435:TMP) at 12 h, and the undesirable dimer and oligomer formation were suppressed. Moreover, the product was recovered easily without extra separation steps, and the biocatalyst and the molecular sieves remained intact for subsequent regeneration and recycling. The reaction of CalB with DMC and the primary transesterification product, monocarbonated TMP, respectively, as acyl donors was evaluated by in silico modeling and empirically to determine the role of the enzyme in the formation of cyclic carbonates and other side products. DMC was shown to be the preferred acyl donor, suggesting that TMP and its carbonated derivatives serve only as acyl acceptors in the lipase-catalyzed reaction. Subsequent cyclization to cyclic carbonate is catalyzed at increased temperature and not by the enzyme.
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| 6. |
- Ching, Tao-Chung, et al.
(author)
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The JCMT BISTRO-2 Survey: Magnetic Fields of the Massive DR21 Filament
- 2022
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 941:2
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Journal article (peer-reviewed)abstract
- We present 850 mu m dust polarization observations of the massive DR21 filament from the B-fields In STar-forming Region Observations (BISTRO) survey, using the POL-2 polarimeter and the SCUBA-2 camera on the James Clerk Maxwell Telescope. We detect ordered magnetic fields perpendicular to the parsec-scale ridge of the DR21 main filament. In the subfilaments, the magnetic fields are mainly parallel to the filamentary structures and smoothly connect to the magnetic fields of the main filament. We compare the POL-2 and Planck dust polarization observations to study the magnetic field structures of the DR21 filament on 0.1-10 pc scales. The magnetic fields revealed in the Planck data are well-aligned with those of the POL-2 data, indicating a smooth variation of magnetic fields from large to small scales. The plane-of-sky magnetic field strengths derived from angular dispersion functions of dust polarization are 0.6-1.0 mG in the DR21 filament and similar to 0.1 mG in the surrounding ambient gas. The mass-to-flux ratios are found to be magnetically supercritical in the filament and slightly subcritical to nearly critical in the ambient gas. The alignment between column density structures and magnetic fields changes from random alignment in the low-density ambient gas probed by Planck to mostly perpendicular in the high-density main filament probed by James Clerk Maxwell Telescope. The magnetic field structures of the DR21 filament are in agreement with MHD simulations of a strongly magnetized medium, suggesting that magnetic fields play an important role in shaping the DR21 main filament and subfilaments.
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| 7. |
- Dishisha, Tarek, et al.
(author)
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Bio-based 3-hydroxypropionic- and acrylic acid production from biodiesel glycerol via integrated microbial and chemical catalysis
- 2015
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In: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 14
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Journal article (peer-reviewed)abstract
- Background 3-Hydroxypropionic acid (3HP) and acrylic acid (AA) are industrially important platform- and secondary chemical, respectively. Their production from renewable resources by environment-friendly processes is desirable. In the present study, both chemicals were almost quantitatively produced from biodiesel-derived glycerol by an integrated process involving microbial and chemical catalysis. Results Glycerol was initially converted in a fed-batch mode of operation to equimolar quantities of 3HP and 1,3-propanediol (1,3PDO) under anaerobic conditions using resting cells of Lactobacillus reuteri as a biocatalyst. The feeding rate of glycerol was controlled at 62.5 mg/gCDW.h which is half the maximum metabolic flux of glycerol to 3HP and 1,3PDO through the L. reuteri propanediol-utilization (pdu) pathway to prevent accumulation of the inhibitory intermediate, 3-hydroxypronionaldehyde (3HPA). Subsequently, the cell-free supernatant containing the mixture of 3HP and 1,3PDO was subjected to selective oxidation under aerobic conditions using resting cells of Gluconobacter oxydans where 1,3PDO was quantitatively converted to 3HP in a batch system. The optimum conditions for the bioconversion were 10 g/L substrate and 5.2 g/L cell dry weight. Higher substrate concentrations led to enzyme inhibition and incomplete conversion. The resulting solution of 3HP was dehydrated to AA over titanium dioxide (TiO2) at 230 °C with a yield of >95 %. Conclusions The present study represents the first report on an integrated process for production of acrylic acid at high purity and -yield from glycerol through 3HP as intermediate without any purification step. The proposed process could have potential for industrial production of 3HP and AA after further optimization.
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| 8. |
- Dishisha, Tarek, et al.
(author)
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Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol
- 2014
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In: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 13
-
Journal article (peer-reviewed)abstract
- Background Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. Results The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Conclusions Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of the engineered RPRB3007 strain, highlighting the potential of metabolic engineering to render an industrially sound strain. This is the first report on the production of 3HP and 1,3PDO as sole products using the wild-type or mutant L. reuteri strains, and has laid ground for further work on improving the productivity of the biotransformation process using resting cells.
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| 9. |
- Doi, Yasuo, et al.
(author)
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The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 899:1
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Journal article (peer-reviewed)abstract
- We present new observations of the active star formation region NGC 1333 in the Perseus molecular cloud complex from the James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. The BISTRO data cover the entire NGC 1333 complex (∼1.5 pc ? 2 pc) at 0.02 pc resolution and spatially resolve the polarized emission from individual filamentary structures for the first time. The inferred magnetic field structure is complex as a whole, with each individual filament aligned at different position angles relative to the local field orientation. We combine the BISTRO data with low- and high- resolution data derived from Planck and interferometers to study the multiscale magnetic field structure in this region. The magnetic field morphology drastically changes below a scale of ∼1 pc and remains continuous from the scales of filaments (∼0.1 pc) to that of protostellar envelopes (∼0.005 pc or ∼1000 au). Finally, we construct simple models in which we assume that the magnetic field is always perpendicular to the long axis of the filaments. We demonstrate that the observed variation of the relative orientation between the filament axes and the magnetic field angles are well reproduced by this model, taking into account the projection effects of the magnetic field and filaments relative to the plane of the sky. These projection effects may explain the apparent complexity of the magnetic field structure observed at the resolution of BISTRO data toward the filament network.
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| 10. |
- Eswaraiah, Chakali, et al.
(author)
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The JCMT BISTRO Survey: Revealing the Diverse Magnetic Field Morphologies in Taurus Dense Cores with Sensitive Submillimeter Polarimetry
- 2021
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 912:2
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Journal article (peer-reviewed)abstract
- We have obtained sensitive dust continuum polarization observations at 850 μm in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope as part of the B-fields in STar-forming Region Observations (BISTRO) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution (∼2000 au or ∼0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis-Chandrasekhar-Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38 ± 14, 44 ± 16, and 12 ± 5 μG, respectively. These cores show distinct mean B-field orientations. The B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. The B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field and not well correlated with other axes. In contrast, Miz-8b exhibits a disordered B-field that shows no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux.
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