Journals
2009 EN
Dabros Michal · Amrhein Michael · Bonvin Dominique
+2 more
Real‐time data reconciliation of concentration estimates of process analytes and biomass in microbial fermentations is investigated. A Fourier‐transform mid‐infrared spectrometer predicting the concentrations of process metabolites is used in parallel with a dielectric spectrometer predicting the biomass concentration during a batch fermentation of the yeast Saccharomyces cerevisiae . Calibration models developed off‐line for both spectrometers suffer from poor predictive capability due to instrumental and process drifts unseen during calibration. To address this problem, the predicted metabolite and biomass concentrations, along with off‐gas analysis and base addition measurements, are reconciled in real‐time based on the closure of mass and elemental balances. A statistical test is used to confirm the integrity of the balances, and a non‐negativity constraint is used to guide the data reconciliation algorithm toward positive concentrations. It is verified experimentally that the proposed approach reduces the standard error of prediction without the need for additional off‐line analysis. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
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Journals
2009 EN
Öncül Alper A. · Kalmbach Andreas · Genzel Yvonne
+2 more
Characterization of flow conditions is of great importance to control cell growth and cell damage in animal cell culture because cell viability is influenced by the flow properties in bioreactors. Alternative reactor types like Wave Bioreactors® have been proposed in recent years, leading to markedly different results in cell growth and product formation. An advantage of Wave Bioreactors® is the disposability of the Polyethylenterephthalet‐bags after one single use (fast setup of new production facilities). Another expected advantage is a lower shear stress compared to classical stirred‐tank reactors, due to the gentle liquid motion in the rocking cellbag. This property would considerably reduce possible cell damage. The purpose of the present study is to investigate in a quantitative manner the key flow properties in Wave Bioreactors®, both numerically and experimentally. To describe accurately flow conditions and shear stress in Wave Bioreactors® using numerical simulations, it is necessary to compute the unsteady flow applying Computational Fluid Dynamics (CFD). Corresponding computations for two reactor scales (2 L and 20 L cellbags) are presented using the CFD code ANSYS‐FLUENT®. To describe correctly the free liquid surface, the present simulations employ the Volume of Fluid (VOF) method. Additionally, experimental measurements have been carried out to determine liquid level, flow velocity and liquid shear stress, which are used as a validation of the present CFD simulations. It is shown that the obtained flows stay in the laminar regime. Furthermore, the obtained shear stress levels are well below known threshold values leading to damage of animal cells. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010
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Journals
2009 EN
Evidente Antonio · Cristinzio Gennaro · Punzo Biancavaleria
+3 more
A 3,5‐disubstituted furan, named flufuran, was isolated from a culture filtrate of a strain of Aspergillus flavus obtained from a chestnut compost created in the same orchard. Flufuran was identified by spectroscopic methods, and its structure was confirmed through the preparation of some key derivatives, also used to test the antifungal activity. At a concentration of 0.2 mg/ml, assayed against three Phytophthora species, pathogenic of some forest and agrarian plants, flufuran and especially its acetyl derivative showed significant antifungal activity. Although flufuran appears to be identical to a fungal metabolite isolated previously from some Polyporus spp., its interesting antifungal activity has never been reported before.
Journals
2009 EN
Gougeon Regis D. · Lucio Marianna · De Boel Arnaud
+9 more
A non‐targeted, ultra‐high‐resolution mass spectrometric, direct analysis of oak‐wood extracts from two species ( Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra‐high‐resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea , respectively, as corroborated by both FTMS and NMR data. For the first time, it is shown that oak woods can also be discriminated on the basis of hundreds of forest‐related compounds, and particular emphasis is put on sessile oaks from the Tronçais forest, for which sugars are significantly discriminant. Despite the higher complexity and diversity of wine metabolites, forest‐related compounds can also be detected in wines aged in related barrels. It is only by using these non‐targeted analyses that such innovative results, which reveal specific chemodiversities of natural materials, can be obtained.
Journals
2009 EN
Bélanger Dominique · Tong Xia · Soumaré Sadia
+2 more
Pepped up polymers : The synthesis and properties of novel chiral cyclic peptides designed to complex with suitable polymers through hydrogen bonding are described. A substituted cyclic peptide self‐assembles into supramolecular nanotubes and develops noncovalent interactions with poly(vinyl alcohol) (PVA) by means of its carboxyl side chains.The efficient synthesis of novel chiral cyclic peptides cyclo[NHCHX‐CHCHCH 2 CO(NHCH 2 CHCHCH 2 CO) 2 ] designed to develop hydrogen‐bonding interactions with suitable polymers is described. Complexation of a carboxylic acid derivatized cyclic peptide 2 (X=CH 2 OCOCH 2 CH 2 CO 2 H) capable of self‐assembling as “endless” tubes, with poly(vinyl alcohol) (PVA) led to a vast weak‐interaction network, in which the cyclopeptide developed extensive hydrogen‐bonding interactions with the hydroxyl groups of PVA through not only the carboxylic acid, but also its ester carbonyl and amide groups. In aqueous solution, the peptide/PVA complexes self‐assemble into long‐grain ricelike aggregates compatible with the stacking of cyclic peptides through intercycle hydrogen bonds. Upon casting on silicon wafer, the anisotropic aggregates can coalesce to form filaments tens of micrometers long. The study demonstrates that complexing functionalized cyclic peptides with polymers through hydrogen bonding is a useful approach for using polymers to mediate the self‐assembly and self‐organization of cyclic peptides.
Journals
2009 EN
Amans Dominique · Bellosta Véronique · Cossy Janine
Jackpot: Two for one! Concise and highly convergent syntheses of the immunosuppressive agent FR252921 and the related antimicrobial natural product pseudotrienic acid B were achieved from one common intermediate by using optically active titanium complexes to control the configuration of the stereogenic centers, a highly stereo‐ and regioselective cross‐metathesis to generate the triene moieties, and a Stille cross‐coupling to install the dienic units.Concise and highly convergent syntheses of the immunosuppressive agent FR252921 and the related antimicrobial natural product pseudotrienic acid B were achieved from a common intermediate by using optically active titanium complexes to control the configuration of the stereogenic centers, a highly stereo‐ and regioselective cross‐metathesis to generate the triene moieties, and a Stille cross‐coupling to install the dienic units.
Journals
2009 EN
Arrachart Guilhem · Creff Gaëlle · Wadepohl Hubert
+11 more
The hydrolysis and condensation of a silylated derivative of ureidopyrimidinone led to nanostructured hybrid silica, such as that depicted, as clearly shown by powder XRD studies. The nanostructuring was directly related to molecular recognition through hydrogen bonding. By combining FTIR, solution and solid‐state NMR spectroscopic data, the transcription of the hydrogen‐bonding networks from the precursor to the final product was clearly evidenced.
Journals
2009 EN
Forestier Thibaut · Kaiba Abdellah · Pechev Stanislav
+6 more
By changing the surfactant/water ratio , nanoparticles of the iron(II) spin crossover material, [Fe(NH 2 ‐trz) 3 ]Br 2 ⋅ 3 H 2 O (with NH 2 ‐trz=4‐amino‐1,2,4‐triazole), have been synthesised from 1 μm down to 30 nm (see figure). Magnetic and reflectivity experiments indicate that the critical size for observing a thermal hysteresis in this 1D polymer family is around 50 nm, and powder X‐ray diffraction shows that particles of about 30 nm are constituted by about one coherent domain.This paper describes the synthesis of iron(II) spin‐crossover nanoparticles prepared by the reverse micelle technique by using the non‐ionic surfactant Lauropal (Ifralan D0205) from the polyoxyethylenic family. By changing the surfactant/water ratio, the size of the particles of [Fe(NH 2 ‐trz) 3 ]Br 2 ⋅3H 2 O (with NH 2 trz=4‐amino‐1,2,4‐triazole) can be controlled. On the macroscopic scale this complex exhibits cooperative thermal spin crossovers at 305 and 320 K. We find that when the size is reduced down to 50 nm, the spin transition becomes gradual and no hysteresis can be detected. For our data it seems that the critical size, for which the existence of a thermal hysteresis can be detected, is around 50 nm. Interestingly, the change of the particle size induces almost no change in the temperature of the thermal spin transition. A systematic determination of coherent domain size carried out on the nanoparticles by powder X‐ray diffraction indicates that at approximately 30 nm individual particles consist of one coherent domain.
Journals
2009 EN
Wane Amadou · Thallaj Nasser K. · Mandon Dominique
We report that the formation of μ‐oxo diferric compounds from O 2 and FeCl 2 complexes within the tris(2‐pyridylmethyl)amine series (N. K. Thallaj et al. Chem. Eur. J. , 2008 , 14 , 6742–6753) involves coordination of O 2 to the metal centre and that this reaction occurs following initial dissociation of the bound equatorial chloride anion. We also report evidence of the formation of a reduced form of dioxygen by an inner‐sphere mechanism, thus leading to modification of the ligand. The solid‐state structures of [FeCl 2 L] complexes (L 1 =mono(α‐pivalamidopyridylmethyl)bis(2‐pyridylmethyl)amine, L 2 =mono(α‐pivalesteropyridylmethyl)bis(2‐pyridylmethyl)amine, L 3 =bis(α‐pivalamidopyridylmethyl)mono(2‐pyridylmethyl)amine are described, and spectroscopic data support the structural retention in solution. In [FeCl 2 L 3 ], the two amide hydrogen atoms stabilise the equatorial chloride anion in such a way that its exchange by a weak ligand is impossible: [FeCl 2 L 3 ] is perfectly oxygen‐stable. In [FeCl 2 L 2 ], the equatorial chloride anion is completely free to move and coordination of O 2 can take place. The reaction product with [FeCl 2 L 2 ] is a μ‐oxo diferric complex in which the ester function has been transformed into a phenol group. This conversion can be seen as a hydrolysis reaction in basic medium, hence supporting the initial formation of a reduced form of dioxygen in the medium. Complex [FeCl 2 L 1 ] exhibits a very weak reactivity with O 2 , in line with a semistabilised equatorial chloride counteranion.
Journals
2009 EN
Jahier Claire · Cantuel Martine · McClenaghan Nathan D.
+6 more
Chirality transfer : Enantiopure dendritic polyoxometalate frameworks were prepared by assembling chiral dendritic amines and acidic POM units. The solution CD, UV/Vis and vibrational CD investigations, and the efficiency of these hybrids in the asymmetric oxidation of thioanisole to sulfoxide (14 % ee ), indicate significant induced optical activity in the POM cluster. Despite the modest ee , the present reaction confirms a chirality transfer to the POM unit.