Designing bioinspired coral-like structures using a templateless electropolymerization approach with a high water content.

Here, with the aim of obtaining densely packed porous nanostructures of various shape using templateless electropolymerization in organic solvent (dichloromethane), original thieno[3,4- b]thiophene-based monomers with different substituents are studied. First of all, the adding of water in solution has a huge influence on the formation of porous structures because a much higher amount of gas (O2 and/or H2) is released. Rigid substituents such as aromatic groups have a beneficial effect on the formation of nanotubular structures contrary to flexible ones such as alkyl chains. Special results are obtained with the pyrene substituent (Thieno-Pyr). With this monomer, coral-like structures are obtained. These structures are obtained by the formation first on long nanotubular structures and their sagging due to their weight. Then, the released gas is trapped inside these structures leading to huge craters. These exceptional surfaces could be used in the future in various potential applications such as in drug delivery, cell growth, sensors, optical devices or surface adhesion. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology (part 2)'.

One F-octyl versus two F-butyl chains in surfactant aggregation behavior.

An easy synthetic procedure in two or three steps from perfluoroalkylethyl iodide derivatives led to six novel fluorinated carboxylates monomeric and gemini surfactants with one or two hydrophobic tails, respectively: RF(C2H4)CH(CO2(-))2,2Na(+) and [RF(C2H4)]2C(CO2(-)),Na(+), where RF = C4F9, C6F13, and C8F17. These anionic surfactants exhibited very low surface tension from 15 to 33 mN/m as well as low critical micelle concentration until 1.3 × 10(-4) mol/L. Furthermore, the surface properties of the gemini compound with two short fluoroalkyl chains (RF = C4F9) were found to be almost equal to those of the monomeric surfactant with one long fluoroalkyl chain (RF = C8F17), which could provide an interesting alternative to the bioaccumulative long-chain perfluorinated surfactant.

Treatment of obstetrical brachial plexus palsy sequelae: Preliminary results about 18 cases.

Background: Severe obstetrical injuries of the brachial plexus lead to a complete or incomplete paralysis resulting in a significant functional handicap of the limb.This study aimed to assess the preliminary results of our management. Materials and methods: This prospective study involved 18 patients, with an average age of 7.7 years. The choice of the surgical technique depended on the type of palsy. We evaluated our patients using the Mallet, Gilbert-Raimondi, Brachial plexus World Group Heerlen, and Raimondi scores. Results: Patients in groups I and II of Narakas had an anterior shoulder release (n = 2) and transfer of the latissimus dorsi (n = 8). For those in group III, we performed 5 biceps rerouting and 2 radius derotation osteotomies, one of which was associated with a Zancolli I and an arthrodesis of the thumb MCP joint. In the wrist and hand, we performed two tendon transfers from the flexor carpi ulnaris to the extensor tendons of the fingers.After a mean follow-up of 30.52 months, in the first 9 patients, active external rotation of the shoulder increased from a mean value of -22.5°-38.8° and mean active abduction from 78.3° to 141.1°. In Group III, the mean spontaneous supination position of 75.5° was improved to 45° pronation. Regarding the two patients with tendon transfers, active wrist extension increased from 0° to 45° and from -60° to 0°, respectively. Conclusion: Palliative surgery in the treatment obstetrical brachial plexus palsy sequelae retains an important place in the restoration of upper limb function.

Determinants of woody cover in African savannas.

Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than approximately 650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered 'stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of approximately 650 mm, savannas are 'unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation may considerably affect their distribution and dynamics.

Parahydrophobic and Nanostructured Poly(3,4-ethylenedioxypyrrole) and Poly(3,4-propylenedioxypyrrole) Films with Hyperbranched Alkyl Chains.

Here, we control the surface hydrophobicity and the adhesion of water droplets by electrodeposition of poly(3,4-ethylenedioxypyrrole) (PEDOP) and poly(3,4-propylenedioxypyrrole) (PProDOP) with branched alkyl chains placed preferentially on the bridge to favor the formation of nanofibers. Branched alkyl chains of various sizes from very short (C3) to hyperbranched (C18) are studied because they have lower surface hydrophobicity than long alkyl or fluoroalkyl chains (preferable for parahydrophobic properties). The electrodeposition is much more favored with the PEDOP derivatives because the ProDOP films are more soluble. However, the formation of nanoparticles is favored with the PEDOP polymers in contrast to the formation of fibers, resembling the wax nanoclusters observed on lotus leaves, with the ProDOP polymers. With both these PEDOP and PProDOP derivatives, it is possible to reach parahydrophobic properties characterized by a sticking behavior toward water droplets. This kind of surfaces could be used in the future in water harvesting systems, for example.

Surface Nanostructuration and Wettability of Electrodeposited Poly(3,4-ethylenedioxypyrrole) and Poly(3,4-propylenedioxypyrrole) Films Substituted by Aromatic Groups.

In the aim to obtain parahydrophobic materials (both high contact angles and high hysteresis) for possible applications in water harvesting systems, we report the synthesis of novel 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) monomers with aromatic rings on the 3,4-alkylenedioxy bridge and the resulting conducting polymer films were prepared by electropolymerization. We show that the surface properties can be tuned by the nature of the aromatic ring (phenyl, biphenyl, diphenyl, naphthalene, fluorene, and pyrene) and the polymerizable core (EDOP or ProDOP). The best results are obtained with both EDOP and diphenyl, with which extremely high hydrophobic properties (up to 116°) are obtained, even if the polymers are intrinsically hydrophilic. These surfaces could be applied in the future, for example, in water harvesting systems or in water/oil separation membranes. The synthesis strategy is extremely interesting, and many other molecules will be envisaged in the future.

Formation of Nanofibers with High Water Adhesion by Electrodeposition of Films of Poly(3,4-ethylenedioxypyrrole) and Poly(3,4-propylenedioxypyrrole) Substituted by Alkyl Chains.

Invited for this month's cover are the collaborating groups of Dr. Thierry Darmanin at Université Côte d'Azur, France, and Dr. Alioune Diouf at Université Cheikh Anta Diop de Dakar, Senegal. The front cover shows nanofibrous surfaces prepared by the electropolymerization of 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) derivatives in which an alkyl chain is grafted to the 3,4-alkylenedioxy bridge. Depending on whether an EDOP or a ProDOP monomer is used, and the length of the alkyl chain, the surface properties of the resulting polymer are very different. Read the full text of the article at 10.1002/cplu.201800279.

Formation of Nanofibers with High Water Adhesion by Electrodeposition of Films of Poly(3,4-ethylenedioxypyrrole) and Poly(3,4-propylenedioxypyrrole) Substituted by Alkyl Chains.

With the aim of controlling the surface hydrophobicity and water adhesion, nanofibrous surfaces were prepared by electropolymerization of 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) derivatives having various alkyl chains (C3 to C17 ) grafted to a 3,4-alkylenedioxy bridge. Depending on whether an EDOP or a ProDOP was used, and the length of the alkyl chain, the surface properties of the resulting polymer were very different. The formation of nanofibrous surfaces was much more favored for ProDOP derivatives. The alkyl chain length has also a huge influence on the formation of nanofibers, and alkyl chains of intermediate length (C9 and C11 ) gave the best results. Apparent contact angles (θw ) of up to 150° were obtained, and the water adhesion properties were highly variable. This work is important for many applications in which the control of interaction forces with a medium is required, such as in oil-water separation membranes or water-harvesting systems.

Superhydrophobic (low adhesion) and parahydrophobic (high adhesion) surfaces with micro/nanostructures or nanofilaments.

Controlling the water adhesion is extremely important for various applications such as for water harvesting. Here, superhydrophobic (low adhesion) and parahydrophobic (high adhesion) substrates are both obtained from hydrophilic polymers. We show in the work that a judicious choice in the monomer structure used for electropolymerization can lead to these two properties. Using a phenyl group, parahydrophobic properties are reached due to the formation of nanofilaments. By contrast, using a naphthalene or a biphenyl group, superhydrophobic properties are obtained due the formation of both micro- and nanostructures.

Open-loop control of a MEMS deformable mirror for large-amplitude wavefront control.

A method is introduced for predicting control voltages that will generate a prescribed surface shape on a MEMS deformable mirror. The algorithm is based upon an analytical elastic model of the mirror membrane and an empirical electromechanical model of its actuators. It is computationally simple and inherently fast. Shapes at the limit of achievable mirror spatial frequencies with up to 1.5 microm amplitudes have been achieved with less than 15 nm rms error.