122 research outputs found
H2 as a fuel for flavin- and H2O2-dependent biocatalytic reactions
The soluble hydrogenase from Ralstonia eutropha provides an atom efficient regeneration system for reduced flavin cofactors using H2 as an electron source. We demonstrated this system for highly selective ene-reductase-catalyzed C[double bond, length as m-dash]C-double bond reductions and monooxygenase-catalyzed epoxidation. Reactions were expanded to aerobic conditions to supply H2O2 for peroxygenase-catalyzed hydroxylations.DFG, 284111627, H2-basierende Kaskaden für die Biosynthese von N-HeterocyclenDFG, 405325648, ,Engineering von O2-toleranten Hydrogenasen und ihre physiologischen Auswirkungen in rekombinanten Bakterien im Hinblick auf die Hydrogenase-abhängige NAD(P)H-Regeneration und H2-ProduktionDFG, 390540038, EXC 2008: UniSysCatTU Berlin, Open-Access-Mittel - 202
Infinite-contrast periodic composites with strongly nonlinear behavior: Effective-medium theory versus full-field simulations
This paper presents a combined numerical-theoretical study of the macroscopic
behavior and local field distributions in a special class of two-dimensional
periodic composites with viscoplastic phases. The emphasis is on strongly
nonlinear materials containing pores or rigid inclusions. Full-field numerical
simulations are carried out using a Fast-Fourier Transform algorithm [H.
Moulinec, P. Suquet, C. R. Acad. Sci. Paris II 318, 1417 (1994)]
Moulinec, P. Suquet, C. R. Acad. Sci. Paris II 318, 1417 (1994), while the
theoretical results are obtained by means of the `second-order' nonlinear
homogenization method [P. Ponte Castaneda, J. Mech. Phys. Solids 50, 737
(2002)]. The effect of nonlinearity and inclusion concentration is investigated
in the context of power-law (with strain-rate sensitivity m) behavior for the
matrix phase under in-plane shear loadings. Overall, the `second-order'
estimates are found to be in good agreement with the numerical simulations,
with the best agreement for the rigidly reinforced materials. For the porous
systems, as the nonlinearity increases (m decreases), the strain field is found
to localize along shear bands passing through the voids (the strain
fluctuations becoming unbounded) and the effective stress exhibits a singular
behavior in the dilute limit. More specifically, for small porosities and fixed
nonlinearity m>0, the effective stress decreases linearly with increasing
porosity. However, for ideally plastic behavior (m = 0), the dependence on
porosity becomes non-analytic. On the other hand, for rigidly-reinforced
composites, the strain field adopts a tile pattern with bounded strain
fluctuations, and no singular behavior is observed (to leading order) in the
dilute limit.Comment: 28 pages, 28 B&W figures, 2 tables of color maps, to be published in
International Journal of Solids and Structures (in press
Co-Designing an organic framework: the ”REF’AB” Project in France
To help the development of Organic Food and Farming (OFF) systems, there is the need to consolidate conversions to OF, to support entry into organic farming, and to develop existing organic farms. Therefore a group of extensionists, researchers and educators has being working 2 years long to co-design a framework for OFF, taking into account the need to (i) embrace all forms of OFF, and at the same time to (ii) address the specificities of OFF. This project, called REF’AB (REFerentiel de l’Agriculture Biologique, 2010-2012) aims at designing the organization of set of references produced on shared methodological bases. The approach consisted in identifying key-issues of OFF systems, defining indicators, identifying relevant databases and references to feed the framework, and providing recommendations for governance to optimise the establishment and circulation of references. The outcomes of this project is that first it was not necessarily clear what a framework for OFF should be, and therefore a conference of consensus was used as a methodological
tool to share views by multi-stakeholders. Second, we used sustainability assessment as an integrative process of the three levels (technical-economic, environmental, and social) and third, to manage to share a more transversal approach, we proposed a framework with 3 levels of key-proprieties: 1) security and efficiency, 2) durability through the protection of resources, and 3) autonomy and resilience
Optical and Radio Properties of Extragalactic Sources Observed by the FIRST and SDSS Surveys
We discuss the optical and radio properties of 30,000 FIRST sources
positionally associated with an SDSS source in 1230 deg of sky. The
majority (83%) of the FIRST sources identified with an SDSS source brighter
than r=21 are optically resolved. We estimate an upper limit of 5% for the
fraction of quasars with broad-band optical colors indistinguishable from those
of stars. The distribution of quasars in the radio flux -- optical flux plane
supports the existence of the "quasar radio-dichotomy"; 8% of all quasars with
i<18.5 are radio-loud and this fraction seems independent of redshift and
optical luminosity. The radio-loud quasars have a redder median color by 0.08
mag, and a 3 times larger fraction of objects with red colors. FIRST galaxies
represent 5% of all SDSS galaxies with r<17.5, and 1% for r<20, and are
dominated by red galaxies. Magnitude and redshift limited samples show that
radio galaxies have a different optical luminosity distribution than non-radio
galaxies selected by the same criteria; when galaxies are further separated by
their colors, this result remains valid for both blue and red galaxies. The
distributions of radio-to-optical flux ratio are similar for blue and red
galaxies in redshift-limited samples; this similarity implies that the
difference in their luminosity functions, and resulting selection effects, are
the dominant cause for the preponderance of red radio galaxies in flux-limited
samples. We confirm that the AGN-to-starburst galaxy number ratio increases
with radio flux, and find that radio emission from AGNs is more concentrated
than radio emission from starburst galaxies (abridged).Comment: submitted to AJ, color gif figures, PS figures available from
[email protected]
The estimation of black-hole masses in distant radio galaxies
We have estimated the masses of the central supermassive black holes of 2442
radio galaxies froma catalog compiled using data from the NED, SDSS, and CATS
databases. Mass estimates based on optical photometry and radio data are
compared. Relationships between the mass of the central black hole
and the redshift are constructed for both wavelength ranges. The
distribution of the galaxies in these diagrams and systematic effects
influencing estimation of the black-hole parameters are discussed.
Upperenvelope cubic regression fits are obtained using the maximum estimates of
the black-hole masses. The optical and radio upper envelopes show similar
behavior, and have very similar peaks in position, , and
amplitude, = 9.4. This is consistent with a model in which the
growth of the supermassive black holes is self-regulating, with this redshift
corresponding to the epoch when the accretion-flow phase begins to end and the
nuclear activity falls off.Comment: 8 pages, 6 figure
Effective-medium theory for infinite-contrast two-dimensionally periodic linear composites with strongly anisotropic matrix behavior: Dilute limit and crossover behavior
Unassisted solar lignin valorisation using a compartmented photo-electro-biochemical cell
Lignin is a major component of lignocellulosic biomass. Although it is highly recalcitrant to break down, it is a very abundant natural source of valuable aromatic carbons. Thus, the effective valorisation of lignin is crucial for realising a sustainable biorefinery chain. Here, we report a compartmented photo-electro-biochemical system for unassisted, selective, and stable lignin valorisation, in which a TiO2 photocatalyst, an atomically dispersed Co-based electrocatalyst, and a biocatalyst (lignin peroxidase isozyme H8, horseradish peroxidase) are integrated, such that each system is separated using Nafion and cellulose membranes. This cell design enables lignin valorisation upon irradiation with sunlight without the need for any additional bias or sacrificial agent and allows the protection of the biocatalyst from enzymedamaging elements, such as reactive radicals, gas bubbles, and light. The photo-electrobiochemical system is able to catalyse lignin depolymerisation with a 98.7% selectivity and polymerisation with a 73.3% yield using coniferyl alcohol, a lignin monomer
Diagnostic yield of next-generation sequencing in very early-onset inflammatory bowel diseases: a multicenter study (vol 12, pg 1104, 2021)
Transplantation and immunomodulatio
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