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The metal-mediated dimerization of oligoquinoline foldamers terminated at one end with an oligo(phenylenevinylene) and at the other with a carboxylic acid (OPV-QnA, where n= 4, 8, 17, and 33), and the complexation of OPV-Q8A and Q16A was promoted in chloroform by the addition of a concentrated 16 M aqueous sodium hydroxide solution. UV–vis absorption and time-resolved fluorescence anisotropy (TRFA) experiments were conducted to determine, respectively, the concentration and the average rotational time ⟨ϕ⟩ of the mixture of unassociated and associated foldamers across a range of foldamer concentrations spanning 5 orders of magnitude. Plots of ⟨ϕ⟩ as a function of acid group concentration revealed that ⟨ϕ⟩ increased with increasing foldamer concentration only when the foldamer solution in chloroform was vigorously mixed with the 16 M sodium hydroxide aqueous solution. Furthermore, all plots showed that ⟨ϕ⟩ reached a plateau at high foldamer concentration. The increase in ⟨ϕ⟩ reflected the association of foldamers into larger objects through metal ion coordination with the carboxylate anions generated by deprotonation of the carboxylic acid of OPV-QnA with NaOH, while the plateau obtained at high foldamer concentration indicated that these interactions led to the dimerization of the foldamers via a closed association mechanism. Analysis of the ⟨ϕ⟩ trends yielded the equilibrium constants (K) describing the foldamer dimerization, whose value equaled 1.0 (±0.2) × 106M–1for the three longer OPV-QnA foldamers, but was about 10 times smaller for the shortest one (n= 4). Association of OPV-Q8A and Q16A yielded a complex with a ⟨ϕ⟩ matching that of OPV-Q24A, and Kfor this complexation was similar to that for dimerization. These experiments illustrate the robust nature of TRFA as an experimental method to probe the size of rigid, self-assembled foldamers in solution.

Flocculation is a type of aggregation where the surfaces of approaching droplets are still at distances no closer than a few nanometers while still remaining in close proximity. In a high internal-phase oil-in-water (O/W) emulsion, the state of flocculation affects the bulk flow behavior and viscoelasticity, which can consequently control the three-dimensional (3D)-printing process and printing performance. Herein, we present the assembly of O/W Pickering high-internal-phase emulsions (Pickering-HIPEs) as printing inks and demonstrate how depletion flocculation in such Pickering-HIPE inks can be used as a facile colloidal engineering approach to tailor a porous 3D structure suitable for drug delivery. Pickering-HIPEs were prepared using different levels of cellulose nanocrystals (CNCs), co-stabilized using “raw” submicrometer-sized sustainable particles from a biomass-processing byproduct. In the presence of this sustainable particle, the higher CNC contents facilitated particle-induced depletion flocculation, which led to the formation of a mechanically robust gel-like ink system. Nonetheless, the presence of adsorbed particles on the surface of droplets ensured their stability against coalescence, even in such a highly aggregated system. The gel structures resulting from the depletion phenomenon enabled the creation of high-performance printed objects with tunable porosity, which can be precisely controlled at two distinct levels: first, by introducing voids within the internal structure of filaments, and second, by generating cavities (pore structures) through the elimination of the water phase. In addition to printing efficacy, the HIPEs could be applied for curcumin delivery, and in vitrorelease kinetics demonstrated that the porous 3D scaffolds engineered for the first time using depletion-flocculated HIPE inks played an important role in 3D scaffold disintegration and curcumin release. Thus, this study offers a unique colloidal engineering approach of using depletion flocculation to template 3D printing of sustainable inks to generate next-generation porous scaffolds for personalized drug deliveries.

Sex and gender differences in Parkinson’s disease should be a priority for researchers and clinicians, to ensure appropriate care is provided to patients.

Adaptive and reversible self-assembly of supramolecular protein structures is a fundamental characteristic of dynamic living matter. However, the quantitative detection and assessment of the emergence of mesoscale protein complexes from small and dynamic oligomeric precursors remains highly challenging. Here, we present a novel approach utilizing a short membrane nanotube (sNT) pulled from a planar membrane reservoir as nanotemplates for molecular reconstruction, manipulation, and sensing of protein oligomerization and self-assembly at the mesoscale. The sNT reports changes in membrane shape and rigidity caused by membrane-bound proteins as variations of the ionic conductivity of the sNT lumen. To confine oligomerization to the sNT, we have designed and synthesized rigid oligoamide foldamer tapes (ROFTs). Charged ROFTs incorporate into the planar and sNT membranes, mediate protein binding to the membranes, and, driven by the luminal electric field, shuttle the bound proteins between the sNT and planar membranes. Using Annexin-V (AnV) as a prototype, we show that the sNT detects AnV oligomers shuttled into the nanotube by ROFTs. Accumulation of AnV on the sNT induces its self-assembly into a curved lattice, restricting the sNT geometry and inhibiting the material uptake from the reservoir during the sNT extension, leading to the sNT fission. By comparing the spontaneous and ROFT-mediated entry of AnV into the sNT, we reveal how intricate membrane curvature sensing by small AnV oligomers controls the lattice self-assembly. These results establish sNT-ROFT as a powerful tool for molecular reconstruction and functional analyses of protein oligomerization and self-assembly, with broad application to various membrane processes.

The surfactant used during a colloidal synthesis is known to control the size and shape of metallic nanoparticles. However, its influence on the nanoparticle (NP) structure is still not well understood. In this study, we show that the surfactant can significantly modify the lattice parameter of a crystalline particle. First, our electron diffraction measurements reveals that NiPt nanoparticles around 4 nm in diameter covered by a mixture of oleylamine and oleic acid (50:50) display a lattice parameter expansion around 2% when compared to the same particles without surfactant. Using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX) techniques, we show that this expansion can not be explained by crystal defects, twinning, oxidation, or atoms insertion. Then, using covered NPs in the 4–22 nm size range, we show that the lattice parameter evolves linearly with the inverse of the NP size, as it is expected when a surface stress is present. Finally, the study is extended to pure nickel and pure platinum NPs, with different sizes, coated by different surfactants (oleylamine, trioctylphosphine, polyvinylpyrrolidone). The surfactants induce lattice parameter variations, whose magnitude could be related to the charge transfer between the surfactant and the particle surface.

A series of aromatic helix-sheet-helix oligoamide foldamers composed of several different photosensitive diazaanthracene units have been designed and synthesized. Molecular objects up to 7 kDa were straightforwardly produced on a 100 mg scale. Nuclear magnetic resonance and crystallographic investigations revealed that helix-sheet-helix architectures can adopt one or two distinct conformations. Sequences composed of an even number of turn units were found to fold in a canonical symmetrical conformation with two helices of identical handedness stacked above and below the sheet segment. Sequences composed of an odd number of turns revealed a coexistence between a canonical fold with helices of opposite handedness and an alternate fold with a twist within the sheet and two helices of identical handedness. The proportions between these species could be manipulated, in some cases quantitatively, being dependent on solvent, temperature, and absolute control of helix handedness. Diazaanthracene units were shown to display distinct reactivity toward [4 + 4] photocycloadditions according to the substituent in position 9. Their organization within the sequences was programmed to allow photoreactions to take place in a specific order. Reaction pathways and kinetics were deciphered and product characterized, demonstrating the possibility to orchestrate successive photoreactions so as to avoid orphan units or to deliberately produce orphan units at precise locations. Strong cooperative effects were observed in which the photoreaction rate was influenced by the presence (or absence) of photoadducts in the structure. Multiple photoreactions within the aromatic sheet eventually lead to structure lengthening and stiffening, locking conformational equilibria. Photoproducts could be thermally reverted.

The scalable synthesis of Pd–NHC cinnamyl complexes supported on benzyloxycalix[8]arene is reported. These catalysts are very active for Buchwald–Hartwig cross-coupling reactions, allowing the coupling of aryl chlorides and bromides with a wide variety of alkyl and aryl amines using low catalytic loadings. The supported complexes also successfully afforded attractive unsymmetrical triarylamines, and in one case, promoted the synthesis of an unprecedented Pd-catalyzed C–H activation product. Thanks to the calixarenic support, the target products could be isolated with low levels of residual palladium, and in some cases, even below the restrictive toxic metal standards applied by the pharmaceutical industry. Through an easy to implement procedure, these perfectly characterised catalysts thus combine the best of homogeneous and heterogeneous catalysis: high efficiency (similar to or even better than the corresponding homogeneous complexes) and low Pd leaching levels expected from heterogeneous catalysts.

Self-assembly is a powerful method to obtain large discrete functional molecular architectures. When using a single building block, self-assembly generally yields symmetrical objects in which all the subunits relate similarly to their neighbours. Here we report the discovery of a family of self-constructing cyclic macromolecules with stable folded conformations of low symmetry, which include some with a prime number (13, 17 and 23) of units, despite being formed from a single component. The formation of these objects amounts to the production of polymers with a perfectly uniform length. Design rules for the spontaneous emergence of such macromolecules include endowing monomers with a strong potential for non-covalent interactions that remain frustrated in competing entropically favoured yet conformationally restrained smaller cycles. The process can also be templated by a guest molecule that itself has an asymmetrical structure, which paves the way to molecular imprinting techniques at the level of single polymer chains.

Aromatic oligoamides adopting helical conformations are synthesized by coupling carboxyl-terminated basic units having two, four, and eight residues to amine-terminated oligomer precursors. Coupling yields show no noticeable reduction with the size of the basic units or the final product. One- and two-dimensional NMR spectroscopy and computational studies demonstrate the reliable helical folding of these oligomers. The X-ray structure of 16mer 7reveals a compact, multiturn helix having a 9 Å inner pore.

This study introduces a global fluorescence decay analysis that substantially simplifies the acquisition and analysis of time-resolved fluorescence decays acquired with a vertically polarized excitation and vertically (IVV(t)) and horizontally (IVH(t)) polarized emission for time-resolved fluorescence anisotropy (TRFA) measurements. TRFA measurements were conducted whereby the IVV(t) and IVH(t) fluorescence decays of a series of oligoquinolines labeled at one end with an oligo(phenylenevinylene) dye (OPV-Qnwith n= 4, 7, 17, 24, 33) were acquired according to the standard protocol that is currently accepted in the scientific literature which involves toggling the emission polarizer before fitting linear combinations of the IVV(t) and IVH(t) decays or acquiring the IVV(t) and IVH(t) decays with static polarizers before fitting them globally. The rotational time (ϕ) and initial anisotropy (r0) retrieved from these analyses were identical within experimental error regardless of whether the decays were acquired with toggling or static polarizers and fitted according to the standard protocol or globally. These experimental results were further supported by retrieving the parameters used to generate mono-, bi-, and tri-exponential TRFAs from the global analysis of simulated IVV(t) and IVH(t) fluorescence decays which were found to match perfectly the values that were inputted. Together, these experiments and simulations demonstrated that the parameters describing any type of TRFA can be extracted directly from the analysis of the IVV(t) and IVH(t) fluorescence decays acquired with a standard time-resolved fluorometer, a substantial simplification compared to the protocols currently in place to determine the TRFA.

Les maladies métaboliques représentent un problème croissant en termes de santé publique. De nombreux polluants ou contaminants alimentaires sont suspectés de participer à l’émergence de ces pathologies par leur action en tant que perturbateurs endocriniens ou obésogènes. Dans cette revue, nous décrirons les nombreuses voies d’entrée de ces xénobiotiques, de la production jusqu’à la consommation des aliments, ainsi que leurs différents modes d’action. Nous traiterons de molécules aussi diverses que les dioxines, les hydrocarbures aromatiques polycycliques, l’acrylamide, les bisphénols, les phtalates ainsi que de plusieurs pesticides dont certains émergents. La variété de ces contaminants alimentaires conduit à considérer également le rôle des mélanges, leur durée et période d’exposition et l’effet des faibles doses.

A series of oligoquinoline carboxamides (Qnwith n= 1–32) were prepared with an oligo(phenylene vinylene) (OPV) fluorophore covalently attached at one end via a rigid amide bond. The fluorescence decays of the OPV-Qnsolutions in chloroform were acquired with a vertically polarized excitation and an emission that was either vertically or horizontally polarized to yield the fluorescence decays IVV(t) and IVH(t), respectively. The IVV(t) and IVH(t) decays were fitted globally assuming a monoexponential anisotropy. The fits were good, indicating that the theoretical triexponential anisotropy of these rigid symmetric top macromolecules was well represented by a single exponential over the range of Qnlengths studied. The rotational time retrieved from the global analysis of the IVV(t) and IVH(t) fluorescence decays was found to increase linearly with increasing oligoquinoline chain length in agreement with the notion that these macromolecules were foldamers that adopted a rigid helical conformation in solution. Furthermore, the hydrodynamic volume of the OPV-Qnconstructs determined from their rotational times perfectly matched that expected from the known dimensions of the Qnsamples obtained from single-crystal X-ray diffraction. Unfortunately, the small aspect ratio of the foldamers prevented the resolution of the separate rotational times that would be expected from symmetric top macromolecules whose geometry could be described as ellipsoids or cylinders. Consequently, reliable values for the D∥and D⊥diffusion coefficients representing the tumbling of the foldamers along and perpendicular to the main axis of the symmetric top macromolecule could not be obtained for the OPV-Qnfoldamers. Nevertheless, the excellent correlation found between the foldamer size and rotational time suggests that time-resolved fluorescence anisotropy is a robust experimental technique to characterize the size and conformation of rigid foldamers in solution.

Ultrafiltration technology is an easy-to-implement, energy-efficient, and selective disinfection method for a wide range of pollutants that can facilitate access to drinking water, one of the major worldwide challenges of this century. The work presented here is the first part of a study investigating an innovative thermo-hydraulic ultrafiltration process. The process is powered by solar thermal energy supplied at 40–70 °C by a simple flat-plate solar collector to pump and pressurize the water to be treated by an ultrafiltration module. The preliminary experimental study carried out and presented in this paper has enabled the characterization of the hydraulic pumping/pressurization devices with an energy efficiency ranging from 0.9 to 0.75. The backwashing device ensured a pressure ratio between the filtration and backwashing, varying between 0.85 and 1.1. A series of 30 min filtration of river water taken downstream of a wastewater treatment plant, carried out at a transmembrane pressure of 1.5 bar and followed by a 3 min backwash, made it possible to achieve a stabilization of the membrane permeability between 70 and 80% of its initial permeability. An unsteady-state numerical model was developed to simulate and analyze the behavior of the process in filtration mode and during backwashing. The average deviations that were observed between simulated and experimental results amounted to 6.4% for flow rates and 1.6% for pressures.

Helically folded aromatic foldamers may constitute suitable candidates for the ab initiodesign of ligands for protein surfaces. As preliminary steps toward the exploration of this hypothesis, a tethering approach was developed to detect interactions between a protein and a foldamer by confining the former at the surface of the latter. Cysteine mutants of two therapeutically relevant enzymes, CypA and IL4, were produced. Two series of ten foldamers were synthesized bearing different proteinogenic side chains and either a long or a short linker functionalized with an activated disulfide. Disulfide exchange between the mutated cysteines and the activated disulfides yielded 20 foldamer-IL4 and 20 foldamer-CypA adducts. Effectiveness of the reaction was demonstrated by LC-MS, by MS analysis after proteolytic digestion, and by 2D NMR. Circular dichroism then revealed diastereoselective interactions between the proteins and the foldamers confined at their surface which resulted in a preferred handedness of the foldamer helix. Helix sense bias occurred sometimes with both the short and the long linkers and sometimes with only one of them. In a few cases, helix handedness preference is found to be close to quantitative. These cases constitute valid candidates for structural elucidation of the interactions involved.

Numerous essential biomolecular processes require the recognition of DNA surface features by proteins. Molecules mimicking these features could potentially act as decoys and interfere with pharmacologically or therapeutically relevant protein–DNA interactions. Although naturally occurring DNA-mimicking proteins have been described, synthetic tunable molecules that mimic the charge surface of double-stranded DNA are not known. Here, we report the design, synthesis and structural characterization of aromatic oligoamides that fold into single helical conformations and display a double helical array of negatively charged residues in positions that match the phosphate moieties in B-DNA. These molecules were able to inhibit several enzymes possessing non-sequence-selective DNA-binding properties, including topoisomerase 1 and HIV-1 integrase, presumably through specific foldamer–protein interactions, whereas sequence-selective enzymes were not inhibited. Such modular and synthetically accessible DNA mimics provide a versatile platform to design novel inhibitors of protein–DNA interactions.

Following exposure to xenobiotics, cellular mechanisms will take place to prevent damages relative to i) DNA, to maintain genome integrity, ii) proteins, to maintain their activities, iii) lipids, to limit peroxidation. This system of cellular defence and resistance is energetically costly. In this commentary review, we discuss the impact of DNA damage and the DNA damage response (DDR) on energetic metabolism. Conversely, we address the question about how energetic metabolism would influence DDR. These points will be highlighted in the context of cancer, in which genome instability and aerobic glycolysis are cancer hallmarks.

Beside their crucial role in xenobiotic biotransformation, AhR and Nrf2 are involved in the regulation of energetic metabolism. Nrf2, as a cytoprotective transcription factor, supply energy for detoxification and antioxidant response. AhR is ligand-activated transcriptional factor implicated in several physiological function. Following pollutant exposure, it acts as a chemosensor to eliminate harmful chemicals. Altogether, AhR and Nrf2 cooperate to contribute to protective responses upon contaminant exposure, including metabolic remodelling. This fine-tuned energetic coupling with detoxification can lead to prominent dysfunction under a chronic exposure to pollutants, and promote a long-term reprogramming that affects multiple cellular activities.

Translation, the mRNA-templated synthesis of peptides by the ribosome, can be manipulated to incorporate variants of the 20 cognate amino acids. Such approaches for expanding the range of chemical entities that can be produced by the ribosome may accelerate the discovery of molecules that can perform functions for which poorly folded, short peptidic sequences are ill suited. Here, we show that the ribosome tolerates some artificial helical aromatic oligomers, so-called foldamers. Using a flexible tRNA-acylation ribozyme—flexizyme—foldamers were attached to tRNA, and the resulting acylated tRNAs were delivered to the ribosome to initiate the synthesis of non-cyclic and cyclic foldamer–peptide hybrid molecules. Passing through the ribosome exit tunnel requires the foldamers to unfold. Yet foldamers encode sufficient folding information to influence the peptide structure once translation is completed. We also show that in cyclic hybrids, the foldamer portion can fold into a helix and force the peptide segment to adopt a constrained and stretched conformation. The extent to which peptide synthesis by the ribosome can tolerate the inclusion of non-peptidic components is not clear. Yet such hybrids would expand the range of ribosomally synthesized structures. Now it has been shown that tRNAs acylated by aromatic foldamers can initiate the ribosomal synthesis of non-cyclic and cyclic foldamer–peptide hybrid molecules. The oligo-aryl segments contain folding information that can control peptide conformation in the hybrids.

Abiotic foldamers, that is foldamers that have backbones chemically remote from peptidic and nucleotidic skeletons, may give access to shapes and functions different to those of peptides and nucleotides. However, design methodologies towards abiotic tertiary and quaternary structures are yet to be developed. Here we report rationally designed interactional patterns to guide the folding and assembly of abiotic helix bundles. Computational design facilitated the introduction of hydrogen-bonding functionalities at defined locations on the aromatic amide backbones that promote cooperative folding into helix–turn–helix motifs in organic solvents. The hydrogen-bond-directed aggregation of helices not linked by a turn unit produced several thermodynamically and kinetically stable homochiral dimeric and trimeric bundles with structures that are distinct from the designed helix–turn–helix. Relative helix orientation within the bundles may be changed from parallel to tilted on subtle solvent variations. Altogether, these results prefigure the richness and uniqueness of abiotic tertiary structure behaviour.

Constructed wetlands (CWs) have been widely applied in mariculture effluents disposal, however, the pollutants removal performance of mariculture wastewater with different salinity, especially the effect of different halophytes in CWs is rarely discussed. In this study, the nutrients removal efficiencies and absolute abundance of nitrogen (N) transformation microbes in CWs microcosms were investigated. With the increase of the salinity, both Phragmites australis (P. australis) and Suaeda salsa (S. salsa) planted CWs showed a significant reduction in chemical oxygen demand removal performance (p < 0.05), while no significant restriction on the nitrogen removal rates of all groups was obtained. The N removal efficiency was even promoted under 1.4% in these two kinds of CWs, respectively. And total phosphorus removal efficiency declined at the salinity of 1.4% and 2.1% for P. australis and S. salsa planted CWs, respectively. Further analysis showed that the presence of nitrification and denitrification was the major approaches of N removal. The absolute abundance of genes related with N transformation genes was significantly influenced by fluctuation of salinity, which affected the treatment efficiency of wastewater. The two different CWs presented high possibility of application on mariculture treatment in proper salinity.

At the molecular level, translation refers to the production of a new entity according to a template that has a different chemical composition. In this way, chemical information may be translated from one molecule to another. The process is useful to synthesize structures and thus functions that might be difficult to create otherwise, and it reaches exquisite levels of efficiency in biological systems, as illustrated by protein expression from mRNA templates or by the assembly of the tobacco mosaic virus capsid protein according to the length of its RNA. In synthetic systems, examples of template-directed syntheses are numerous, but general and versatile schemes in which a non-natural sequence actually encodes the information necessary to produce a different sequence are few and far from being optimized. Here we show a high-fidelity enzyme-free translation of long rod-like alkylcarbamate oligomers into well-defined sequences of stacked helical aromatic oligoamides. The features present in the rods, which include the number and distance between carbamate functions and stereogenic centres, template the self-assembly of complementary stacks of helices that each have a defined right (P) or left (M) handedness, length and single or double helicity. This process enables the production of very large (>20 kDa) abiotic artificial folded architectures (foldamers) that may, for example, serve as scaffolds to organize appended functional features at positions in space defined with atomic precision across nanometric distances.

Heavy oil, extra-heavy oil and tar sands account for half of the petroleum resources of the world. Due to their high viscosity their production is a major technical and economical challenge. The understanding of the origin and geological habitat of these unconventional oils is crucial in order to optimize exploration and production operations. The vast majority of these heavy oils originates from the biodegradation of conventional oils by bacterial activity. The limiting factors of the involved biological processes (temperature, nutrients, etc.) are controlled by the geological situation. In this respect, foreland basins which harbour a large part of the current deposits of heavy oils correspond to particularly favourable conditions in promoting the biodegradation of large charges of oil. They are characterized by long distance lateral oil migration draining substantial volume of the petroleum system. This migration is supported by an adequate drainage system which exhibits a large lateral continuity and consists of the first syntectonic fluvial and fluvial-deltaic sediments filling the foreland basins. As a result of this migration the oil reaches shallow situation in the forebulge where the temperature is compatible with bacterial activity. The reservoirs associated with the “forebulge” are often high porosity and high permeability sand bodies, initially hosting large volume of water and facilitating the circulation of meteoric water helping in the nutrient availability. For the sake of production, the heterogeneities associated with these fluvial and fluvial-deltaic sediments have to be carefully considered. The geological models developed for the architecture and for the stratigraphic evolution of fluvial channels and incised valleys provide useful guidelines in order to characterize the reservoirs for production purposes in such geological setting. The technical difficulties in recovering these highly viscous fluids require to integrate more detailed reservoir description than usually needed when producing conventional oil plays. The Cretaceous reservoirs of the Mannville Formation in Canada is presented to exemplify the types of heterogeneities encountered in fluvial reservoirs, their rational, their effect on the heavy oil recovery and the impact of the geological knowledge on the production strategy.

The petroleum deposits in the South Atlantic are considered in terms of the contemporary understanding of the formation of petroleum and of the petroleum system concept. These hydrocarbon reserves (7% of the global reserves), contained in the sedimentary rims along the coasts of West Africa and of the Eastern seaboard of South America, result from a favourable geological setting that is essentially the same on both sides of the ocean, giving rise to an almost symmetrical pattern. Their history is described within the general framework of the opening of the South Atlantic Ocean, which began over 140 Ma ago with the breaking up of the proto-continent Pangea. The importance of these concepts for the opening up of deep and ultra-deep offshore prospects in West Africa and Brazil is underlined.

Following a short review of the evolution of petroleum organic geochemistry in recent decades, this paper depicts the present status of research in the field and describes the guidelines dictated by the needs of the operators. Today, the industrial players are interested in increasingly deep prospects (high pressure, high temperature), in the exploration of the deep offshore, the search for gas and in the production of the planet's enormous heavy oil reserves. In this context, the challenge is to contribute effectively to the quantitative prediction of the oil and gas reserves at the scale of a basin (volume, composition, uncertainties) and to predict the quality of the fluids present in a reservoir, through a closer knowledge of the geochemical events affecting their preservation and their alteration.

In the context of reducing production costs for the oil industry, this paper aims to suggest a way for predicting wax precipitation at an early stage of the reservoir characterization and production process. In this respect, reservoir core extracts and production oil-saturated fractions have been herein analyzed by high temperature gas chromatography (HTGC) in order to quantify the high molecular weight hydrocarbons (HMWHC) which are at the origin of wax deposits in the tubing and surface facilities. Samples of oils and associated reservoir cores from two adjacent but non-communicating fields are considered in this paper. Wax deposition is documented for Field P but not for Field A. It is demonstrated that the reservoir core extract of Field P is substantially enriched in HMWHC when compared to the produced oil, whereas for Field A, with no production problems, both profiles (oil and reservoir core extracts) are similar and depleted in HMWHC. These results suggest that fields exhibiting a risk of wax precipitation could be identified during the exploration phase as soon as reservoir cores are available. Moreover, it can be envisioned that such additional data provided by the saturates distribution can potentially be used in future thermodynamic models (derived from those currently applied for assessing wax precipitation in pipelines during the transport of produced oil) in order to quantitatively predict, at an early stage of reservoir characterization, paraffins precipitation in reservoirs and tubings during production. The preliminary computed results obtained for the produced oil and the reservoir rock extract of Field P indicate that the temperature of paraffin crystallization onset is significantly under-estimated when using the composition of tank oil (42°C)-heavy paraffins are already deposited. On the other hand, the predictive calculation, using the core extract (52°C) and which can be performed as soon as a core sample is available, will allow us to minimize the risk of paraffin deposition during production and transportation. Corresponding author (I. Kowalewski)

Dynamic foldamers are synthetic folded molecules which can change their conformation in response to an external stimulus and are currently at the forefront of foldamer chemistry. However, constitutionally dynamic foldamers, which can change not only their conformation but also their molecular constitution in response to their environment, are without precedent. We now report a size- and shape-switching small dynamic covalent foldamer network which responds to changes in pH. Specifically, acidic conditions direct the oligomerization of a dipeptide-based building block into a 16-subunit macrocycle with well-defined conformation and with high selectivity. At higher pH the same building block yields another cyclic foldamer with a smaller ring size (9mer). The two foldamers readily and repeatedly interconvert upon adjustment of the pH of the solution. We have previously shown that addition of a template can direct oligomerization of the same building block to yet other rings sizes (including a 12mer and a 13mer, accompanied by a minor amount of 14mer). This brings the total number of discrete foldamers that can be accessed from a single building block to five. For a single building block system to exhibit such highly diverse structure space is unique and sets this system of foldamers apart from proteins. Furthermore, the emergence of constitutional dynamicity opens up new avenues to foldamers with adaptive behavior.

The synthesis of helical aromatic oligoamide foldamers derived from 8-amino-2-quinolinecarboxylic acid is described. The precursors are commercially available and products up to and including the octamer are obtained. The procedure covers the synthesis of the monomer, reduction of N-terminal nitro groups into amines, saponification of C-terminal methyl esters to form carboxylic acids, and coupling of amines and acids to form amides via acid chloride activation. Emphasis is given to how these reactions can be scaled up and how purification can be greatly simplified using recrystallization methods, thus providing considerable improvements over previously described procedures. As an illustration of the improvement, 8.4 g of an octamer can now reliably be prepared from a nitro-ester monomer in a matter of 8 (working) weeks without any chromatography.

Progesterone with its anti-seizure effect plays a role in the pathophysiology of catamenial epilepsy which affects 31–60% of epileptic women. In this study, an attempt to treat women suffering from catamenial epilepsy with progesterone, as an adjuvant drug, was made.

Background: Progesterone with its anti-seizure effect plays a role in the pathophysiology of catamenial epilepsy which affects 31-60% of epileptic women. In this study, an attempt to treat women suffering from catamenial epilepsy with progesterone, as an adjuvant drug, was made. Methods: The treatment was given to 36 women aged 20–40 years (mean age: 30.75± 6.05) with seizuresinthe entire second half of the menstrual cycle, who were found to have low serum levels of progesterone on days 22, 27, 28 of the cycle in comparison with a control group of healthy women. The patients were administered progesterone in a daily dose of 50 mg on days 16–25 of each cycle. The serum levels of antiepileptic drugs were assayed. The period of progesterone therapy ranged from 3 to 45 months (17.7 on average). Results: Three patients were free of secondary generalized seizures, and one - of simple partial seizures. A decline in the frequency of primary and secondary generalized seizures by 20-96% (55.9% on average) was accomplished in 18 patients (primary general-izedby20-96% - 54.7%on average, and secondarily generalized by 38-85% - 59%on average). Adeclinein the frequencyof complex partial seizures by 38-87% (63.1% on average) was achieved in 15 women. In 1 patient, the frequency of myoclonic seizures decreased by 46%. There was no improvement in 5 women (3 patients with generalized, 1 with complex partial and 1 with simple partial seizures). An exacerbation of seizure frequency occurred in 5 patients. Adverse effects were not found in any of the subjects. The average concentrations of antiepileptic drugs during hormonal therapy were in the therapeutic range. Conclusion: Progesterone combined with antiepileptic therapy was well tolerated and resulted in a significant reduction of seizure frequency in majority of patients with catamenial epilepsy.

A new simple and cost-effective method has been developed for the fabrication of both plano-convex and plano-concave lens arrays with potentially important sag heights. The process is based on the use of potassium bromide (KBr) powder. At ambient temperature and under pressure, KBr powder is compressed on a molding die with the desired shape to form a solid lens array. The quality of the lens arrays has been assessed, and we present the first image produced by a converging KBr lens array.

Finest selection: Side‐chain selective, end‐group selective, diastereoselective, and RNA‐ vs. DNA‐selective interactions have been revealed between multiturn helical aromatic amide foldamers having cationic side chains and G‐quadruplex aptamers.

Feine Auswahl: Zwischen helicalen aromatischen Amidfoldameren mit mehreren Windungen und kationischen Seitenketten und G‐Quadruplex‐Aptameren wurden verschiedene Arten von Wechselwirkungen aufgeklärt: Seitenketten‐selektive, Endgruppen‐selektive, diastereoselektive und RNA‐ vs. DNA‐selektive.

Screwed in place: An anti‐parallel double‐helical aromatic oligoamide foldamer was shown to bind to a series of rodlike guests of various lengths upon the winding of the duplex around the guests (see scheme). Solid‐state crystal structures of the host–guest complexes show that the two strands of the duplex undergo a relative screw motion to adjust the distance between hydrogen‐bond donors located at the end of one of their extremities so that they bind to hydrogen‐bond acceptors of the guest.

Eingewickelt: Ein antiparalleles doppelhelicales aromatisches Oligoamid‐Foldamer bindet stabförmige Gastspezies verschiedener Länge durch Umwinden (siehe Schema). Kristallstrukturanalysen der Wirt‐Gast‐Komplexe im Festkörper zeigen, dass die beiden Stränge eine Schraubenbewegung gegeneinander ausführen, um den Abstand zwischen Wasserstoffbrücken‐Donoren an jeweils einem ihrer Enden so einzustellen, dass sie an Wasserstoffbrücken‐Akzeptoren des Gastes binden können.

A detailed investigation of the 4‐(benzyloxy)phenol/formaldehyde reaction shows that along with the previously described p‐(benzyloxy)calix[8]arene and p‐(benzyloxy)calix[6]arene, others calixarenes are observed and easily recovered on a preparative scale. All these new calixarenes are opening interesting perspectives for the synthesis of new supramolecular hosts, easily functionalized at the paraposition under very mild conditions and/or exhibiting a deep hydrophobic pocket.

Synthesis of alternating pyridine–pyrrole molecular strands composed of two electron‐rich pyrrole units (donors) sandwiched between three pyridinic cores (acceptors) is described. The envisioned strategy was a smooth electrosynthesis process involving ring contraction of corresponding tripyridyl–dipyridazine precursors. 2,6‐Bis[6‐(pyridazin‐3‐yl)]pyridine ligands 2 a–cbearing pyridine residues at the terminal positions were prepared in suitable quantities by a Negishi metal cross‐coupling procedure. The yields of heterocyclic coupling between 2‐pyridyl zinc bromide reagents 12 a–cand 2,6‐bis(6‐trifluoromethanesulfonylpyridazin‐3‐yl)pyridine increased from 68 to 95 % following introduction of electron‐donating methyl groups on the metallated halogenopyridine units. Favorable conditions for preparative electrochemical reduction of tripyridyl–dipyridazines 2 b,cwere established in THF/acetate buffer (pH 4.6)/acetonitrile to give the targeted 2,6‐bis[5‐(pyridin‐2‐yl)pyrrol‐2‐yl]pyridines 1 band 1 cin good yields. The absorption behavior of the donor–acceptor tripyridyl–dipyrrole ligands was evaluated and compared to theoretical calculations. Highly fluorescent properties of these chromophores were found (νem≈2×104cm−1in MeOH and CH2Cl2), and both pyrrolic ligands exhibit a remarkable quantum yield in CH2Cl2(ϕf=0.10). Structural studies in the solid state established the preferred cisconformation of the dipyrrolic ligands, which adopting a planar arrangement with an embedded molecule of water having a complexation energy exceeding 10 kcal mol−1. The ability of the tripyridyl–dipyrrole to complex two copper(II) ions in a pentacoordinate square was investigated.

We study a weighted improper coloring problem motivated by a frequency allocation problem. It consists of associating to each vertex a set of p(v)(weight) distinct colors (frequencies), such that the set of vertices having a given color induces a graph of degree at most k(the case k = 0corresponds to proper coloring). The objective is to minimize the number of colors. We propose approximation algorithms to compute such a coloring for general graphs. We apply these to obtain good approximation ratio for grid and hexagonal graphs. Furthermore we give exact results for the 2-dimensional grid and the triangular lattice when the weights are all the same.

Oligoamides of 2,6‐diaminopyridine and 2,6‐pyridinedicarboxylic acid comprised of 5, 7, 9, 11, or 13 units and bearing 4‐isobutoxychains on all pyridine rings and tert‐butyl‐carbamate terminal groups have been synthesized stepwise, along with an 11 mer having benzyl‐carbamate terminal groups. The crystal structure of all five Boc‐terminated compounds has been obtained and shows a highly regular and conserved double helical hybridization motif of up to 3 complete turns for the 13 mer. Four pyridine units span one helical turn and define a helix pitch of ca7 Å. Solution studies in CDCl3demonstrated that the Boc‐terminated oligomers strongly hybridize in this solvent, and that Kdimvalues increase with oligomer length. The Kdimvalues are 31000 and 7×105L mol−1for the 7 mer and the 9 mer, respectively, and are too high to be measured by NMR for the 11 mer and the 13 mer. Hybridization and dissociation kinetics at 2 mMproceed at decreasing rates upon increasing oligomer length. The rate was faster than minutes for the 7 mer, of the order of hours for the 9 mer, and days for the 11 mer and 13 mer. The same trend was observed in [D5]pyridine but with considerably lower Kdimvalues and faster kinetics. The benzylcarbamate 11 mer was also found to hybridize into a double helix but with reduced Kdimvalues and faster kinetics compared to its Boc‐terminated analogue. Combined with previous studies, the results presented here frame a global understanding of the hybridization of these pyridinecarboxamide oligomers and provide useful guidelines for the design of other artificial double helices.

Partial methylation of pbenzyloxycalix[6]arene leads to the corresponding trimethylated C3vderivative. This compound was used for the synthesis of new functional calixarenes. The presence of the pbenzyloxy substituent allows this new C3vderivative to be directly oxidized to the trisquinone. These new C3vderivatives open the way to new supramolecular receptors, bearing easily derivatized hydroxy groups at the upper rim position.

Drei, nicht mehr und nicht weniger, ist die Zahl von Naphthyridin‐Oligoamid‐Strängen, die sich zu einer robusten Dreifachhelixarchitektur umeinander winden. Ob die helicalen Stränge eine parallele oder antiparallele Anordnung einnehmen, wird von Faktoren wie der Polarität des Lösungsmittels bestimmt (siehe Bild).

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This contribution presents an application of electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) to study the molecular and supramolecular chirality in assemblies of gemini-tartrate amphiphiles. Nonchiral dicationic n-2-namphiphiles (n= 14–20) can self-organize into right- or left-handed structures upon interacting with chiral tartrate counterions. Micellar solutions can also be obtained for shorter alkyl chains (n= 12). First, the conformation of tartrate counterions has been investigated in various environments (micellar solutions and chiral ribbons). ECD and VCD spectra recorded in micellar solutions are independent from the solvent and from the nature of the cations (sodium, cetyl-trimethylammonium, or dimeric surfactant 12-2-12) used and are representative of the anticonformation of the tartrate dianions. On the other hand, drastic changes in the ECD and VCD spectra have been observed in multilayered chiral assemblies of 16-2-16 tartrate. These strong spectral modifications are associated with the chiral arrangement of the tartrate molecules at the surface of the bilayers. Moreover, chirality transfer from counterions to achiral amphiphiles has been clearly evidenced by VCD since circular dichroism has been observed on vibrations related to alkyl chains and gemini headgroups. Finally, ECD and VCD experiments were performed varying the enantiomeric excess of the tartrate. The ECD and VCD intensities do not vary linearly with the enantiomeric excess of the anion and different behaviors have been observed from the two spectroscopic methods: ECD intensities are correlated to the pitch of the ribbons, whereas the VCD intensities are correlated to the dimension of the chiral ribbons. Chirality 21:E153–E162, 2009. © 2009 Wiley-Liss, Inc.

In this manuscript, we present supramolecular capsules based on a new design relying on both self‐assembly and folding of oligomeric strands. We have designed an aromatic amide foldamer in which each monomer encodes three levels of information: a specific cavity size, recognition groups for guest binding, and a propensity to adopt a single or a double helical motif. Thus, a tetradecameric sequence based on four different monomers was encoded so that a wide double helical segment resulting from the hybridization of two strands creates a cavity in which guests, such as 1,10‐decanediol, can be bound. Additionally two narrow single helical segments form end‐caps and isolate the guest from the solvent. The design, synthesis, solid‐state and solution‐state characterization of duplex formation and guest binding are presented.

Systemic change: A system of transformations between helical structures was observed to be governed by interactions mediated by the electronic effects of substituents, entropic effects, the conformational preferences of organic building blocks, and the coordinative preferences of the metal ion. All of these effects were important, but all must be considered together to allow the prediction of the product observed (see scheme).

This work introduces a biscysteine ligand to build a small peptidic model system of hydrogenase enzymes. FeC5H4CO–Cys–OMe2LH2 has been employed as a chelate for an iron–carbonyl complex, which mimics two essential structural properties of the hydrogenase class of enzymes, namely the coordination of the iron–carbonyl core to peptide ligands and the presence of an electrochemical relay in spatial proximity. The treatment of LH2with Fe3CO12yields LFe2CO63a, which is the first peptidecoordinated iron hydrogenase activesite model complex. Compound 3awas fully characterized spectroscopically 1H NMR, 13C NMR, IR and Mössbauer spectroscopy, mass spectrometry and elemental analysis. A singlecrystal Xray analysis confirms the proposed structure and reveals a staggered conformation of the Fe2CO6S2core. Fourier transform infrared FTIR spectroelectrochemistry reveals an electronic interaction between the peptide backbone and the iron–carbonyl cluster, but not with the ferrocene subsite. The introduction of this peptidic cysteinebased ligand into hydrogenase model chemistry helps to confirm the proposed cofactor biosynthesis and understand the electronic interplay between the metal–carbonyl active site and the protein environment in this important class of enzymes.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008

Foldamers at an angle: Metal‐directed assembly dictates the perpendicular or parallel orientation of helically folded aromatic oligoamide modules and mediates the communication of their relative handedness (see figure).

L’informatique a envahi notre société, modifié nos pratiques quotidiennes, transformé les méthodes de travail. Toute l’information produite, transmise, traitée, stockée dans ces nouvelles pratiques est sous forme numérique. Les obsolescences constantes de la technologie et l’absence d’organisations appropriées rendent cette information de plus en plus vulnérable au temps. La pérennisation de cette information pose des problèmes nouveaux à nombre d’organismes et d’entreprises. La recherche scientifique n’échappe pas à cette difficulté. Une norme fondamentale, le modèle de référence OAIS, nous permet de comprendre en profondeur le problème posé. Ce modèle constitue une base indispensable pour concevoir des solutions qui commencent à voir le jour.

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