Artificial Tendrils Mimicking Plant Movements by Mismatching Modulus and Strain in Core and Shell

Motile organs have evolved in climbing plants enabling them to find a support and, after secure attachment, to reach for sunlight without investing in a self-supporting stem. Searching movements, the twining of stems, and the coiling of tendrils are involved in successful plant attachment. Such coiling movements have great potential in robotic applications, especially if they are reversible. Here, the underlying mechanism of tendril movement based on contractile fibers is reported, as illustrated by a function–morphological analysis of tendrils in several liana species and the encoding of such a principle in a core–shell multimaterial fiber (MMF) system. MMFs are composed of a shape-memory core fiber (SMCF) and an elastic shell. The shape-memory effect of the core fibers enables the implementation of strain mismatch in the MMF by physical means and provides thermally controlled reversible motion. The produced MMFs show coiling and/or uncoiling behavior, with a high reversible actuation magnitude of ≈400%, which is almost 20 times higher compared with similar stimuli for sensitive soft actuators. The movements in these MMFs rely on the crystallization/melting behavior of oriented macromolecules of SMCF

A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene.

BACKGROUND: Familial ovarian cancer (OC) cases not harbouring pathogenic variants in either of the BRCA1 and BRCA2 OC-predisposing genes, which function in homologous recombination (HR) of DNA, could involve pathogenic variants in other DNA repair pathway genes. METHODS: Whole exome sequencing was used to identify rare variants in HR genes in a BRCA1 and BRCA2 pathogenic variant negative OC family of French Canadian (FC) ancestry, a population exhibiting genetic drift. OC cases and cancer-free individuals from FC and non-FC populations were investigated for carrier frequency of FANCI c.1813C>T; p.L605F, the top-ranking candidate. Gene and protein expression were investigated in cancer cell lines and tissue microarrays, respectively. RESULTS: In FC subjects, c.1813C>T was more common in familial (7.1%, 3/42) than sporadic (1.6%, 7/439) OC cases (P = 0.048). Carriers were detected in 2.5% (74/2950) of cancer-free females though female/male carriers were more likely to have a first-degree relative with OC (121/5249, 2.3%; Spearman correlation = 0.037; P = 0.011), suggesting a role in risk. Many of the cancer-free females had host factors known to reduce risk to OC which could influence cancer risk in this population. There was an increased carrier frequency of FANCI c.1813C>T in BRCA1 and BRCA2 pathogenic variant negative OC families, when including the discovery family, compared to cancer-free females (3/23, 13%; OR = 5.8; 95%CI = 1.7-19; P = 0.005). In non-FC subjects, 10 candidate FANCI variants were identified in 4.1% (21/516) of Australian OC cases negative for pathogenic variants in BRCA1 and BRCA2, including 10 carriers of FANCI c.1813C>T. Candidate variants were significantly more common in familial OC than in sporadic OC (P = 0.04). Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the Fanconi anaemia (FA) pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level, destabilized by DNA damaging agent treatment in both HeLa and OC cell lines, and exhibited sensitivity to cisplatin but not to a poly (ADP-ribose) polymerase inhibitor. By tissue microarray analyses, FANCI protein was consistently expressed in fallopian tube epithelial cells and only expressed at low-to-moderate levels in 88% (83/94) of OC samples. CONCLUSIONS: This is the first study to describe candidate OC variants in FANCI, a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that pathogenic FANCI variants may modify OC risk in cancer families

Synthese und Strukturierung von Polymeren Halbleitern: Triphenylamine und Triazine

Zusammenfassung In der vorliegenden Arbeit konnte die neuartige Synthese von Triphyenylamin- und Triazin-Monomeren gezeigt werden. Die hergestellten Monomere konnten sowohl frei als auch lebend radikalisch polymerisiert werden, wodurch sich aus beiden Verbindungen Blockcopolymere herstellen ließen. Mittels GPC und DSC Messungen konnte die erhaltene Blockstruktur nachgewiesen werden. In Cyclovoltammetrie Messungen konnten die Elektronen-leitenden und Loch-leitenden Eigenschaften der Homopolymere nachgewiesen werden. Darüber hinaus war es mit diesen Messungen möglich, die Elektronen-leitenden und Loch-leitenden Blöcke dieser Blockcopolymere gezielt anzusprechen.Weiterhin wurden zwei neue Strukturierungsverfahren für Polymere entwickelt. In dem ersten Verfahren wurden dabei harte Siliziumstempel benutzt, so dass Strukturen im Nanometerbereich generiert werden konnten. Der gesamte Strukturierungsprozess konnte bei Raumtemperatur durchgeführt werden, was einen wesentlichen Zeitvorteil gegenüber NIL entspricht. Weiterhin wurden Linienstrukturen durch das Stempeln mit weichen Silikonstempeln hergestellt. Unabhängig ihrer Herstellungsmethode wirken diese Linienstrukturen als Orientierungsschichten für flüssigkristallines Polyfluoren, wobei die bis heute größte Fluoreszens-Anisotropie auf einem Lochleiter von 1:24 erhalten wurde. Somit sind OLEDs die polarisiertes Licht emittieren möglich.Im zweiten neuartigen Strukturierungsverfahren konnten getrennte Polymerstrukturen aus Loch- und Elektronenleitern durch Bestrahlen einer Monomermischung mit Licht erzeugt werden. Dieses Verfahren bietet den Vorteil, dass kein Material entfernt werden muss und die Strukturierung somit in einem Schritt erfolgt.Abstract In this work the noval synthesis of triphenylamine and triazine monomers was shown. These monomers were polymerized under free radical or living radical conditions. Furthermore block copolymers were synthesized. The obtained block structure was verified by GPC and DSC measurements. In cyclic voltammetry measurements hole – and electron conducting properties of the homopolymers were shown. Additionally it was possible to address the hole and electron conducting properties of the block copolymers individually. Also two new patterning methods were developed. In the first method hard silicon stamps were used, so that line structures in the nanometer range could be generated. The hole process could be performed at room temperature, which is a great time advantage in comparison to NIL. Furthermore by imprinting with soft PDMS stamps line structures were generated. Both line structures act as orienting layer for liquid crystalline polyfluorenes with the until now highest fluorescence anisotropy of 1:24. Therefore OLEDs which emit polarized light are possible. In the second new patterning method separated structures of hole and electron conductors were generated by the irradiation of the monomers with light. This method offers great advantages, as no material has to be removed and the pattering occurs in one step

Light-induced demixing of hole or electron transporting moieties

This paper describes the synthesis of two tri-phenylamine monomers (hole conducting) and one triazine monomer (electron conducting) which differ in their copolymerization parameters because of their styrene and vinyl ester nature. A blend of triphenylamine monomer and poly-(ethylene glycol) and mixtures of both types of monomers (triphepylamine and triazine) were illuminated through a line mask, creating laterally modulated radicals, thus leading to lateral demixing. The experiments with mixtures of triphenylamine and triazine monomers show that the concentration of p- or n-type polymers can be modulated laterally in a controlled way

Light-induced demixing of hole or electron transporting moieties

\u3cp\u3eThis paper describes the synthesis of two tri-phenylamine monomers (hole conducting) and one triazine monomer (electron conducting) which differ in their copolymerization parameters because of their styrene and vinyl ester nature. A blend of triphenylamine monomer and poly-(ethylene glycol) and mixtures of both types of monomers (triphepylamine and triazine) were illuminated through a line mask, creating laterally modulated radicals, thus leading to lateral demixing. The experiments with mixtures of triphenylamine and triazine monomers show that the concentration of p- or n-type polymers can be modulated laterally in a controlled way.\u3c/p\u3

Structural performance of a climbing cactus: making the most of softness

International audienceClimbing plants must reach supports and navigate gaps to colonize trees. This requires a structural organization ensuring the rigidity of so-called ‘searcher’ stems. Cacti have succulent stems adapted for water storage in dry habitats. We investigate how a climbing cactus Selenicereus setaceus develops its stem structure and succulent tissues for climbing. We applied a ‘wide scale’ approach combining field-based bending, tensile and swellability tests with fine-scale rheological, compression and anatomical analyses in laboratory conditions. Gap-spanning ‘searcher’ stems rely significantly on the soft cortex and outer skin of the stem for rigidity in bending (60–94%). A woody core contributes significantly to axial and radial compressive strength (80%). Rheological tests indicated that storage moduli were consistently higher than loss moduli indicating that the mucilaginous cortical tissue behaved like a viscoelastic solid with properties similar to physical or chemical hydrogels. Rheological and compression properties of the soft tissue changed from young to old stages. The hydrogel–skin composite is a multi-functional structure contributing to rigidity in searcher stems but also imparting compliance and benign failure in environmental situations when stems must fail. Soft tissue composites changing in function via changes in development and turgescence have a great potential for exploring candidate materials for technical applications

Cactus-inspired design principles for soft robotics based on 3D printed hydrogel-elastomer systems

International audiencePlants have evolved many capabilities to anchor, position their stems and leaves favourably, and adapt themselves to different environmental conditions by virtue of growing. Selenicereus setaceus is a cactus and is an impressive example of a climbing plant found mostly in the Atlantic forest formations of southern Brazil. This cactus displays striking changes in stem geometry along different stages of growth: older parts are circular while the younger parts are star-like in shape. Such a transformation in shape optimizes its flexural rigidity and allows the cactus to search in three-dimensionally complex environments. Its organisation offers novel schemes for the design of plant-inspired soft robotic systems. In this paper, we have created multi-material systems for soft robotics that display controlled movements as well as mimicking the cactus stem geometries from star-like to circular. The unique star-shaped geometry is 3D printed using a soft elastomer and hydrogel is used as an actuating component. Through anisotropic swelling, the hydrogel-elastomer system adjusts its configuration and shows a controlled movement. Furthermore, the isotropic swelling of the hydrogel of the artificial cactus multi-material system result in the change in shape from star-like to circular as the cactus does naturally in the tropical forest

Bio-Inspired Magnetically Controlled Reversibly Actuating Multimaterial Fibers

Movements in plants, such as the coiling of tendrils in climbing plants, have been studied as inspiration for coiling actuators in robotics. A promising approach to mimic this behavior is the use of multimaterial systems that show different elastic moduli. Here, we report on the development of magnetically controllable/triggerable multimaterial fibers (MMFs) as artificial tendrils, which can reversibly coil and uncoil on stimulation from an alternating magnetic field. These MMFs are based on deformed shape-memory fibers with poly[ethylene-co-(vinyl acetate)] (PEVA) as their core and a silicone-based soft elastomeric magnetic nanocomposite shell. The core fiber provides a temperature-dependent expansion/contraction that propagates the coiling of the MMF, while the shell enables inductive heating to actuate the movements in these MMFs. Composites with mNP weight content ≥ 15 wt% were required to achieve heating suitable to initiate movement. The MMFs coil upon application of the magnetic field, in which a degree of coiling N = 0.8 ± 0.2 was achieved. Cooling upon switching OFF the magnetic field reversed some of the coiling, giving a reversible change in coiling ∆n = 2 ± 0.5. These MMFs allow magnetically controlled remote and reversible actuation in artificial (soft) plant-like tendrils, and are envisioned as fiber actuators in future robotics applications