first_imgDes virus pour mimer la complexité de la natureDes scientifiques et ingénieurs américains se sont servis de virus pour créer de toutes pièces des structures complexes. Selon une étude publiée hier, ce type de procédé pourrait permettre de mettre au point de nouveaux matériaux.Depuis toujours, l’homme cherche à imiter la nature. S’il était autrefois fasciné par les oiseaux qui volent et les poissons qui vivent sous l’eau, les scientifiques s’intéressent aujourd’hui à l’architecture complexe des molécules. Ils cherchent à s’en inspirer pour créer des biomatériaux innovants en mimant le vivant : un procédé appelé “biomimétisme”.”Nous sommes très curieux de comprendre comment la nature peut créer une multiplicité de structures et de fonctions à partir de simples briques de base, comme le collagène pour les animaux ou la cellulose pour les plantes”, explique Seung-Wuk Lee, un scientifique à la tête d’une équipe de chercheurs américains.Selon la façon dont s’orientent et s’agencent ses fibres, le collagène peut former les tissus transparents de la cornée, ceux colorés de la peau ou intervenir dans la formation des os, précise TV5monde. Une auto-organisation à différentes échelles qui surpasse en complexité ce que l’homme peut produire en utilisant des méthodes de fabrication traditionnelles, soulignent les scientifiques dans la revue Nature.Des structures connues dans la nature ou encore inéditesÀ lire aussiPourquoi l’eau des océans est-elle salée ?Ils ont donc utilisé directement des “matériaux” vivants pour parvenir à imiter la complexité de la nature. Ils ont eu recours à des virus de bactéries, les phages M13, comme outils de taille nanométrique. Conservés dans une solution salée où étaient plongées des lames de verre auxquelles ils pouvaient se fixer, ces phages filamenteux ont constitués trois types de films différents. Il a suffi pour cela de jouer sur la concentration de la solution, la proportion de virus qu’elle contenait et la vitesse à laquelle les lames de verre en étaient extraites.Chacun des trois films possédait des propriétés propres et des couleurs et une iridescence variées. Les uns étaient une alternance de bandes de filaments, les autres des rubans en hélice et des paquets de filaments hélicoïdaux ondulant en vagues pour les troisièmes. “Nous avons non seulement imité les structures biologiques, nous avons aussi découvert des structures qu’on n’avait vues ni dans la nature ni en laboratoire”, soulignent les chercheurs. Ils ont également réussi à faire croître des couches de cellules biologiques en prenant pour supports les films créés par les virus. Ce procédé pourrait donc être utilisé pour créer de nouveaux matériaux à base de cristaux liquides ou permettre de réparer les tissus biologiques.Le 21 octobre 2011 à 19:32 • Maxime Lambertlast_img

admin |

Related Posts

The rebels reportedly captured the northern city of Bambari on Sunday, having earlier seized the area around Bria, and are now said to be advancing toward the capital, Bangui. “These developments gravely undermine the peace agreements in place and the efforts of the international community to consolidate peace in the Central African Republic,” Mr. Ban’s spokesperson said a statement issued on Wednesday night. “The Secretary-General deeply regrets the loss of life and population displacement caused by the fighting,” the spokesperson added. He further noted that Mr. Ban appealed to all parties to refrain from “any acts of violence against civilians, including sexual and gender-based violence,” and to ensure the protection of civilians and to respect human rights, in conformity with international instruments to which CAR is a party. The UN chief also urged all parties to abide by the decisions of the Summit of the Heads of State of the Economic Community of Central African States (ECCAS), held in the Chadian capital of N’Djamena on 21 December, which provide a basis for a peaceful resolution of the dispute. In addition, the Secretary-General reminded the CAR Government of its responsibility to ensure the safety and security of UN personnel and its premises. The world body is temporarily relocating dependents and non-essential staff amid the latest violence. “The temporary relocation is a precautionary measure to reduce our presence in the event the security situation further deteriorates in Bangui,” said UN spokesperson Martin Nesirky. “The decision is temporary and will not detract from the ability of the United Nations to continue its support to the peace consolidation and development efforts in the Central African Republic.” Meanwhile, the Secretary-General’s Special Representative and Head of the UN Integrated Peacebuilding Office in the CAR (BINUCA), Margaret Vogt, continues to engage the Government and the rebel leaders with a view to ensuring a ceasefire and initiating dialogue, as recommended by ECCAS on 21 December. Earlier this month, Ms. Vogt condemned all violations of the 2008 peace accord which helped bring a degree of stability to CAR, which has a history of political instability and recurring armed conflict. State authority is weak in many parts of the country, which are largely controlled by rebel groups and criminal armed groups, according to the UN Department of Political Affairs (DPA). BINUCA had played a key role in encouraging the signing of the so-called Libreville Comprehensive Peace Agreement between the Government and three main rebel groups, as well as the holding in December 2008 of the Inclusive Political Dialogue between the Government, rebel groups, the political opposition, civil society and other relevant stakeholders. In yesterday’s statement, Mr. Ban confirmed the UN’s readiness to continue to support CAR in overcoming challenges to the consolidation of peace, in collaboration with regional and international partners.

Residents on the Isle of Skye have removed hundreds of stacks from tourist spots and one of the Canary Islands, Tenerife, calls for the practice to be bannedGlenshee Ski Centre was approached for comment.   Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily  Front Page newsletter and new  audio briefings. A ski centre has been accused of being ‘irresponsible’ after encouraging visitors to build stone stacks in the Scottish mountains. Glenshee Ski Centre near Braemar, Aberdeenshire, was criticised after positing a picture of the mounds on its social media, asking people to build their own. There were more than ten stacks shown in the images, which the ski centre captioned: “Stone sculptures at top of Cairnwell Chair come and add to them. ” The trend, which involves creating stone piles, has taken off as a recreational activity in recent years thanks in part to their popularity on social media. The post however prompted backlash over the potential environmental damage they can cause. Facebook user, Alistair MacDonald said: “Shocked at Glenshee sharing this. I guess they are just a business and don’t care about fragile habitats, nature and the environment. ”Ceàrdach Gàidhealforsa claimed to have reported the ski centre to the Environment Agency.John Hourston, Founder of the Blue Planet Society, said: “In some areas stone-stacking has reached plague proportions and is highly destructive.“The craze appears to be driven by increasing globalised tourism and the desire for an ‘I was here’ photo for social media. ”He added: “We would encourage local authorities where stone-stacking is a problem to ban the practice.”

first_imgComcast is looking to expand their Xfinity services to not only include video, phone, and broadband Internet, but home security as well. After using Dallas as their test market, the company announced this week that it is now prepared to offer the service in six additional cities including Philadelphia, Portland, Jacksonville, Sarasota/Naples, Chattanooga and Nashville. The service will not only include 24/7 professional monitoring in addition to police and fire alarm protection, but will give consumers the ability to adjust digital thermostats, turn lights on/off, and watch secure live streaming video from wireless cameras while outside of the home.Many of the remote security controls offered through the service as well as the live streaming video will be available through a web portal as well as through the new Xfinity Security App for the iPhone which is available as a free download through the iTunes App Store.AdChoices广告Comcast is leveraging Xfinity broadband to bring additional services to home security including access to widgets through a tablet-like touch screen that includes access to weather, news, traffic and sports scores. Customers with Xfinity Voice will even be able to listen to voicemail through an app on the security interface. Additional features include real-time email and text alerts when doors open or close or when motion detectors detect activity inside or outside the home. Battery and cellular backup is also available to keep the system up and running in the event of a power outage.The Xfinity Home Security Preferred Package is currently being offered for as low as $39.95 a month.Other telecommunication companies looking to offer their own home security service include Verizon which announced its Home Monitoring and Control service at CES in January. A trial of the service is currently available to broadband customers in New Jersey.via Comcast.last_img

Leave a Reply

Your email address will not be published. Required fields are marked *