Le jus de canne à sucre en Egypte- assab

Sugarcane as food

n most countries where sugarcane is cultivated, there are several foods and popular dishes derived from it, such as:

* Direct consumption of raw sugarcane cylinders or cubes, which are chewed to extract the juice, and the bagasse is spat out
* Freshly extracted juice (garapa, guarab, guarapa, guarapo, papelón, 'aseer asab, Ganna sharbat, mosto or caldo de cana) by hand or electrically operated small mills, with a touch of lemon and ice, makes a popular drink.
* Molasses, used as a sweetener and as a syrup accompanying other foods, such as cheese or cookies
* Rapadura, a candy made of flavored solid brown sugar in Brazil, which can be consumed in small hard blocks, or in pulverized form (flour), as an add-on to other desserts.
* Sugarcane is also used in rum production, especially in the Caribbean.
* Cane sugar syrup was the traditional sweetener in soft drinks for many years, but has been largely supplanted (in the US at least) by high-fructose corn syrup, which is less expensive, but is considered by some to not taste quite like the sugar it replaces.
* Hard rock candy is a confection that is enjoyed by people around the world.
* Jaggery - solidified molasses of sugarcane, known as Gur or Gud in South Asia. Traditionally produced by heat evaporating sugarcane juice until it is a thick sludge and then letting it cool in buckets used as molds. Modern production methods make use of partial freeze drying to give reduce caramelization and give it lighter color. It is used as sweetener in cooking traditional meal entrees as well as sweets and desserts.
Nitrogen fixation

Some sugarcane varieties are known to be capable of fixing atmospheric nitrogen in association with a bacterium, Acetobacter diazotrophicus. Unlike legumes and other nitrogen fixing plants which form root nodules in the soil in association with bacteria, Acetobacter diazotrophicus lives within the intercellular spaces of the sugarcane's stem.

Cane ethanol

Main article: Ethanol fuel

This is generally available as a by-product of sugar mills producing sugar. It can be used as a fuel, mainly as a biofuel alternative to gasoline, and is widely used in cars in Brazil. It is steadily becoming a promising alternative to gasoline throughout much of the world and thus instead of sugar may be produced as a primary product out of sugar canes processing.

A textbook on renewable energy[7] describes the energy transformation:
At present, 741 tons of raw sugar cane are produced annually per hectare in Brazil. The cane delivered to the processing plant is called burned and cropped (b&c) and represents 77% of the mass of the raw cane. The reason for this reduction is that the stalks are separated from the leaves (which are burned and whose ashes are left in the field as fertilizer) and from the roots that remain in the ground to sprout for the next crop. Average cane production is, therefore, 58 tons of b&c per hectare per year.

Each ton of b&c yields 740 kg of juice (135 kg of sucrose and 605 kg of water) and 260 kg of moist bagasse (130 kg of dry bagasse). Since the higher heating value of sucrose is 16.5 MJ/kg, and that of the bagasse is 19.2 MJ/kg, the total heating value of a ton of b&c is 4.7 GJ of which 2.2 GJ come from the sucrose and 2.5 from the bagasse.

Per hectare per year, the biomass produced corresponds to 0.27 TJ. This is equivalent to 0.86 W per square meter. Assuming an average insolation of 225 W per square meter, the photosynthetic efficiency of sugar cane is 0.38%.

The 135 kg of sucrose found in 1 ton of b&c are transformed into 70 liters of ethanol with a combustion energy of 1.7 GJ. The practical sucrose-ethanol conversion efficiency is, therefore, 76% (compare with the theoretical 97%).

One hectare of sugar cane yields 4000 liters of ethanol per year (without any additional energy input because the bagasse produced exceeds the amount needed to distill the final product). This however does not include the energy used in tilling, transportation, and so on. Thus, the solar energy-to-ethanol conversion efficiency is 0.13%.

Sugarcane

Milling

Sugarcane first has to be moved to a mill which is usually located close to the area of cultivation. Small rail networks are a common method of transporting the cane to a mill.Once the factories acquire the cane it will be subjected to the quality test. In Sri Lanka cane will be evaluated according to the brix and trash percentage.
In a sugar mill, sugarcane is washed, chopped, and shredded by revolving knives. The shredded cane is repeatedly mixed with water and crushed between rollers; the collected juices (called garapa in Brazil) contain 10–15 percent sucrose, and the remaining fibrous solids, called bagasse, are burned for fuel. Bagasse makes a sugar mill more than self-sufficient in energy; the surplus bagasse can be used for animal feed, in paper manufacture, or burned to generate electricity for the local power grid.

The cane juice is next mixed with lime to adjust its pH to 7. This mixing arrests sucrose's decay into glucose and fructose, and precipitates out some impurities. The mixture then sits, allowing the lime and other suspended solids to settle out, and the clarified juice is concentrated in a multiple-effect evaporator to make a syrup about 60 percent by weight in sucrose. This syrup is further concentrated under vacuum until it becomes supersaturated, and then seeded with crystalline sugar. Upon cooling, sugar crystallizes out of the syrup. A centrifuge is used to separate the sugar from the remaining liquid, or molasses. Additional crystallizations may be performed to extract more sugar from the molasses; the molasses remaining after no more sugar can be extracted from it in a cost-effective fashion is called blackstrap.

Raw sugar has a yellow to brown colour. If a white product is desired, sulfur dioxide may be bubbled through the cane juice before evaporation; this chemical bleaches many color-forming impurities into colourless ones. Sugar bleached white by this sulfitation process is called "mill white", "plantation white", and "crystal sugar". This form of sugar is the form most commonly consumed in sugarcane-producing countries. Traditionally, sugarcane has been processed in two stages. Sugarcane mills, located in sugarcane-producing regions, extract sugar from freshly harvested sugarcane, resulting in raw sugar for later refining, and in "mill white" sugar for local consumption. Sugar refineries, often located in heavy sugar-consuming regions, such as North America, Europe, and Japan, then purify raw sugar to produce refined white sugar, a product that is more than 99 percent pure sucrose. These two stages are slowly becoming blurred. Increasing affluence in the sugar-producing tropics has led to an increase in demand for refined sugar products in those areas, where a trend toward combined milling and refining has developed.

[edit] Refining
The Santa Elisa sugarcane processing plant, one of the largest and oldest in Brazil, is located in Sertãozinho, Brazil.
Evaporator with baffled pan and foam dipper for making ribbon cane syrup. Three Rivers Historical Society Museum at Browntown, South Carolina

In sugar refining, raw sugar is further purified. It is first mixed with heavy syrup and then centrifuged clean. This process is called 'affination'; its purpose is to wash away the outer coating of the raw sugar crystals, which is less pure than the crystal interior. The remaining sugar is then dissolved to make a syrup, about 70 percent by weight solids.

The sugar solution is clarified by the addition of phosphoric acid and calcium hydroxide, which combine to precipitate calcium phosphate. The calcium phosphate particles entrap some impurities and absorb others, and then float to the top of the tank, where they can be skimmed off. An alternative to this "phosphatation" technique is 'carbonatation,' which is similar, but uses carbon dioxide and calcium hydroxide to produce a calcium carbonate precipitate.

After any remaining solids are filtered out, the clarified syrup is decolorized by filtration through a bed of activated carbon; bone char was traditionally used in this role, but its use is no longer common. Some remaining colour-forming impurities adsorb to the carbon bed. The purified syrup is then concentrated to supersaturation and repeatedly crystallized under vacuum, to produce white refined sugar. As in a sugar mill, the sugar crystals are separated from the molasses by centrifuging. Additional sugar is recovered by blending the remaining syrup with the washings from affination and again crystallizing to produce brown sugar. When no more sugar can be economically recovered, the final molasses still contains 20–30 percent sucrose and 15–25 percent glucose and fructose.

To produce granulated sugar, in which the individual sugar grains do not clump together, sugar must be dried. Drying is accomplished first by drying the sugar in a hot rotary dryer, and then by conditioning the sugar by blowing cool air through it for several days.
Ribbon cane syrup

Ribbon cane is a subtropical type that was once widely grown in southern United States, as far north as coastal North Carolina. The juice was extracted with horse or mule-powered crushers; the juice was boiled, like maple syrup, in a flat pan, and then used in the syrup form as a sweetener for other foods. It is not a commercial crop nowadays, but a few growers try to keep alive the old traditions and find ready sales for their product. Most sugarcane production in the United States occurs in Florida and Louisiana, and to a lesser extent in Hawaii and Texas.

Sugarcane

Saccharum is a genus of 6 to 37 species (depending on taxonomic interpretation) of tall perennial grasses (family Poaceae, tribe Andropogoneae) commonly known as sugarcane or sugar cane. Native to the warm temperate to tropical regions of the Old World, they have stout, jointed, fibrous stalks that are rich in sugar and measure 2 to 6 meters tall. All of the sugar cane species interbreed, and the major commercial cultivars are complex hybrids.
Scientific classification
Kingdom: Plantae
Phylum: Magnoliophyta
(unranked): Monocots
(unranked): Commelinids
Order: Poales
Family: Poaceae
Genus: Saccharum
Species

Saccharum arundinaceum
Saccharum bengalense
Saccharum edule
Saccharum officinarum
Saccharum procerum
Saccharum ravennae
Saccharum robustum
Saccharum sinense
Saccharum spontaneum

Cultivation and uses
About 195 countries grow the crop to produce 1,324.6 million tons (more than six times the amount of sugar beet produced). As of the year 2005, the world's largest producer of sugar cane by far is Brazil followed by India.[1] Uses of sugar cane include the production of sugar, Falernum, molasses, rum, soda, cachaça (the national spirit of Brazil) and ethanol for fuel. The bagasse that remains after sugar cane crushing may be burned to provide both heat - used in the mill - and electricity, typically sold to the consumer electricity grid. It may also, because of its high cellulose content, be used as raw material for paper, cardboard, and eating utensils branded as "environmentally friendly" as it is made from a by-product of sugar production.
For a longer history, see History of sugar.
Sugarcane was originally from tropical South Asia and Southeast Asia.[3] Different species likely originated in different locations with S. barberi originating in India and S. edule and S. officinarum coming from New Guinea.[3] The thick stalk stores energy as sucrose in the sap. From this juice, sugar is extracted by evaporating the water. Crystallized sugar was reported 5000 years ago in India.

Around the eighth century A.D., Arabs introduced sugar to the Mediterranean, Mesopotamia, Egypt, North Africa, and Spain. By the tenth century, sources state, there was no village in Mesopotamia that didn't grow sugar cane.[2] It was among the early crops brought to the Americas by Spaniards. Brazil is currently the biggest sugar cane producing country.
A boiling house was used in the 17th through 19th centuries to make sugarcane juice into raw sugar. These houses were add-ons to the sugar plantations in the western colonies. This process was often conducted by the African slaves, under very poor conditions. The boiling house was made of cut stone. The furnaces were rectangular boxes of brick or stone with openings near to one side, and at the bottom to stoke the fire and pull out the ashes. At the top of each furnace were up to seven copper kettles or boilers, each one smaller than the previous one and hotter. The cane juice was placed in the first copper kettle which was the largest. The juice was then heated and a little lime added to remove impurities. The juice was then skimmed then channeled to the other copper kettles. The last kettle, which was called the 'teache' was where the cane juice became syrup. It was then put into cooling troughs where the sugar crystals hardened around a sticky core of molasses. The raw sugar was then shoveled from the cooling trough into hogsheads (wooden barrels) where they were put in the curing house.

Sugarcane was, and still is, extensively grown in the Caribbean, where it was first brought by Christopher Columbus during his second voyage to The Americas, initially to the island of Hispaniola (modern day Haiti and the Dominican Republic) . In colonial times, sugar was a major product of the triangular trade of New World raw materials, European manufactures, and African slaves. France found its sugarcane islands so valuable it effectively traded its portion of Canada, famously dubbed "a few acres of snow," to Britain for their return of Guadeloupe, Martinique and St. Lucia at the end of the Seven Years' War. The Dutch similarly kept Suriname, a sugar colony in South America, instead of seeking the return of the New Netherlands (New Amsterdam). Cuban sugarcane produced sugar that received price supports from and a guaranteed market in the USSR; the dissolution of that country forced the closure of most of Cuba's sugar industry. Sugarcane remains an important part of the economy of Belize, Barbados, Haiti along with the Dominican Republic, Guadeloupe, Jamaica, and other islands. The sugarcane industry is a major export for the Caribbean, but it is expected to collapse with the removal of European preferences by 2009.
Sugarcane production greatly influenced many tropical Pacific islands, including Okinawa and most particularly Hawaii and Fiji. In these islands, sugar cane came to dominate the economic and political landscape after the arrival of powerful European and American agricultural business, which promoted immigration from various Asian countries for workers to tend and harvest the crop. Sugar-industry policies eventually established the ethnic makeup of the island populations that now exist, profoundly affecting modern politics and society in the islands.
Brazil is a major grower of sugarcane, which is used to produce sugar and provide the ethanol used in making gasoline-ethanol blends (gasohol) for transportation fuel. In India, sugarcane is sold as jaggery and also refined into sugar, primarily for consumption in tea and sweets, and for the production of alcoholic beverages.
Sugarcane cultivation requires a tropical or subtropical climate, with a minimum of 600 mm (24 in) of annual moisture. It is one of the most efficient photosynthesizers in the plant kingdom. It is a C-4 plant, able to convert up to 2 percent of incident solar energy into biomass.[citation needed] In prime growing regions, such as Peru, Brazil, Bolivia, Colombia, Australia, Ecuador, Cuba, the Philippines and Hawaii, sugarcane can produce 20 kg for each square meter exposed to the sun.[citation needed]

Sugarcane is propagated from cuttings, rather than from seeds; although certain types still produce seeds, modern methods of stem cuttings have become the most common method of reproduction. Each cutting must contain at least one bud, and the cuttings are usually planted by hand. Once planted, a stand of cane can be harvested several times; after each harvest, the cane sends up new stalks, called ratoons. Usually, each successive harvest gives a smaller yield, and eventually the declining yields justify replanting. Depending on agricultural practice, two to ten harvests may be possible between plantings.[citation needed]

Sugarcane is harvested mostly by hand and sometimes mechanically. Hand harvesting accounts for more than half of the world's production, and is especially dominant in the developing world. When harvested by hand, the field is first set on fire. The fire spreads rapidly, burning away dry dead leaves, and killing any venomous snakes hiding in the crop, but leaving the water-rich stalks and roots unharmed. With cane knives or machetes, harvesters then cut the standing cane just above the ground. A skilled harvester can cut 500 kg of sugarcane in an hour.[citation needed]
Sugarcane mechanical harvest in Jaboticabal, São Paulo state, Brazil.

With mechanical harvesting, a sugarcane combine (or chopper harvester), a harvesting machine originally developed in Australia, is used. The Austoft 7000 series was the original design for the modern harvester and has now been copied by other companies including Cameco and John Deere. The machine cuts the cane at the base of the stalk, separates the cane from its leaves, and deposits the cane into a haulout transporter while blowing the thrash back onto the field. Such machines can harvest 100 tonnes of cane each hour, but cane harvested using these machines must be transported to the processing plant rapidly; once cut, sugarcane begins to lose its sugar content, and damage inflicted on the cane during mechanical harvesting accelerates this decay.

Sugar cane is cultivated in almost all the world only for some months of the year
Processing

Traditionally, sugarcane has been processed in two stages. Sugarcane mills, located in sugarcane-producing regions, extract sugar from freshly harvested sugarcane, resulting in raw sugar for later refining, and in "mill white" sugar for local consumption. Sugar refineries, often located in heavy sugar-consuming regions, such as North America, Europe, and Japan, then purify raw sugar to produce refined white sugar, a product that is more than 99 percent pure sucrose. These two stages are slowly becoming blurred. Increasing affluence in the sugar-producing tropics has led to an increase in demand for refined sugar products in those areas, where a trend toward combined milling and refining has developed.

Canne à sucre

Le terme canne à sucre désigne un ensemble d'espèces de plantes de la famille des Poaceae et du genre Saccharum.

Elles sont cultivées pour leurs tiges, dont on extrait du sucre. Avec un volume annuel de production supérieur à 1,3 milliard de tonnes[1], ce sont les premières plantes cultivées au plan mondial avec près de 23% de la masse totale produite en agriculture dans le monde.

Elles furent jusqu'au début du XIXe siècle la seule source importante de sucre et représentent toujours actuellement 65 à 70% de la production de sucre[2].
Plusieurs espèces du genre Saccharum
* Saccharum arundinaceum
* Saccharum bengalense
* Saccharum edule
* Saccharum officinarum
* Saccharum procerum
* Saccharum ravennae
* Saccharum robustum
* Saccharum sinense
* Saccharum spontaneum
La canne à sucre contient environ:

* 71 % d'eau;
* 14 % de saccharose;
* 13 à 14 % de fibres ligneuses;
* 2 à 3 % d'impuretés.

Dans le cadre de l'agriculture biologique, les cannes, sans leurs feuilles, sont pressées plusieurs fois pour en extraire le jus (70 à 80 %), le reste (20 à 30 %) est appelé bagasse. À partir de ce jus, on obtient plusieurs types de sucres: * les sucres totalement pourvus de leur mélasse:
o le jus simplement séché donne le rapadura (dix litre de jus en fournissent environ un kilo),
o le jus épaissi, cristallisé (par addition de cristaux de sucre) puis déshydraté donne le sucre complet;
* les sucres partiellement séparés de leur mélasse par centrifugation et cristallisés:
o le sucre de canne roux véritable,
o le sucre blond.
En agriculture intensive, les champs de canne à sucre sont brûlés et les cannes ramassées mécaniquement. Divers procédés physiques et chimiques permettent d'en extraire le saccharose pur: une tonne de canne fournit environ cent quinze kilos de saccharose.

Sucre

Le sucre est un produit alimentaire d'origine végétale, composé pour l'essentiel de saccharose, et de diverses substances naturelles appartenant à la classe des glucides, responsables d'une des quatre saveurs gustatives fondamentales: le sucré.
Le saccharose est présent dans toutes les plantes contenant de la chlorophylle. Les sucres commercialisés sont essentiellement produits industriellement, à partir de la canne à sucre et de la betterave sucrière. D'autres sources sont utilisées pour produire le glucose ou le fructose de plus en plus utilisés par l'industrie agroalimentaire et d'autres industries[1].
D'autres végétaux contiennent une quantité importante de sucre. Ils sont traditionnellement vendus sous forme de sirop:
* l'érable,
* le palmier-dattier (sucre de palme provenant de la sève, sucre de datte provenant du fruit),
* les palmiers à sucre (comme le cocotier du Chili),
* le sorgho,
* l'agave américain.

Le goût sucré est une saveur utilisée principalement pour son information sur l'apport énergétique de l'aliment et chez l'être humain pour le plaisir qui lui est associé. Son goût est doux.

Le goût sucré est reconnu par une famille de récepteurs couplés à la protéine G T1R1, T1R2 et T1R3 (les mêmes que pour l'umami), ils s'assemblent en homodimères ou hétérodimères et permettent la reconnaissance des sucres naturels ou artificiels.

À part les sucres, de nombreuses autres molécules, artificielles ou naturelles, possèdent un goût sucré, celles-ci ne sont pas toutes reconnues par tous les animaux. Parmi les molécules naturelles on trouve les acides aminés (glycine), les protéines (thaumatine, mabinline), des hétérosides (stéviosides), etc. Parmi les molécules artificielles on trouve, aussi des acides aminés (aspartame), des sulfamate (acésulfame potassium), etc.

Chez l'homme les récepteurs s'associent principalement sous la forme T1R2+T1R3 et lui permettent de reconnaître la majorité des sucres.

Trois centimes de papier et de ruban adhésif pour le diagnostic des maladies

Un nouvel instrument d'analyse microfluidique pourrait améliorer les services de soins dans les pays en développement.
Par Daniel Gorelick
Rédacteur

Washington - À l'aide de papier et de ruban adhésif, des savants ont mis au point un instrument peu coûteux qui permet d'effectuer des analyses sur les liquides organiques pour déterminer la présence de maladies. Cet outil diagnostique de technicité modeste pourrait devenir extrêmement bénéfique dans le secteur de la santé publique des pays pauvres.

Ces instruments de diagnostic tridimensionnels, composés de papier de microanalyse des liquides organiques (test micropapier - 3D microPAD), sont petits, faciles à transporter et n'ont besoin ni de pompe ni d'électricité pour fonctionner. Ils sont donc bien adaptés aux pays en développement, ont indiqué les chercheurs Andres Martinez, Scott Phillips et George Whitesides, de l'université Harvard, dans l'édition du 16 décembre du journal de l'Académie nationale des Sciences des États-Unis d'Amérique.
M. Whitesides est professeur de chimie ; il a dirigé les recherches sur cet instrument de diagnostic et a fondé une organisation à but non lucratif, baptisée Diagnostics-For-All ou Diagnostic pour tous, pour faire en sorte que cette nouvelle technologie puisse parvenir aux pays en développement.

« En mettant au point un outil de diagnostic peu coûteux, utilisable à grande échelle, et qui puisse servir dans des régions qui n'ont guère d'accès à du matériel de laboratoire complexe, nous espérons avoir un impact réel sur la santé publique », écrit M. Whitesides.

En octobre, les laboratoires Whitesides ont mis au point une centrifugeuse en utilisant un fouet à œufs de deux dollars, des tubes de plastique et du ruban adhésif. Cet instrument peut servir à séparer le plasma du sang, préalable nécessaire à de nombreuses analyses médicales.

Les instruments de microanalyse de liquides organiques

Dans les instruments de microanalyse de liquides organiques, ces derniers sont manipulés dans de très petits espaces, souvent de moins d'un millimètre (soit un millième de mètre) - imaginez de l'eau passant par un tube microscopique. De tels canaux microscopiques peuvent être gravés dans de la (du) silicone, du verre, du plastique, ou, comme le cas présent, dans du papier.

L'instrument expérimental (papier microfluidique - 3D micropad) est un carton de plusieurs centimètres carré, capable de détecter les niveaux de sucre et de protéines dans les urines - symptômes du diabète et de l'insuffisance rénale.

Lorsqu'un échantillon de liquide organique est appliqué sur un coin du papier test, ce liquide glisse dans les microcanaux jusqu'à la zone de détection où ont déjà été appliqués des produits chimiques capables de mesurer les niveaux de sucre ou de protéines. Une fois que les liquides organiques touchent cette zone de détection, une réaction chimique se produit et l'endroit cible sur le papier change de couleur, reflétant la quantité de sucre ou de protéines présente.

Ces tests sont achevés en une trentaine de minutes. La couleur peut être observée et interprétée par du personnel ayant une formation minime.

Les microcanaux peuvent conduire un seul échantillon vers plusieurs zones de détection, permettant au personnel médical d'effectuer des tests multiples des niveaux de sucre, un processus nécessaire à une évaluation précise.
Un second avantage qu'offre le micro papier est le fait qu'il est possible de tester plusieurs échantillons sur le même carton - les microcanaux se chevauchent mais, tels des tuyaux placés les uns près des autres, il n'y a pas de connexions entre eux qui permettent aux liquides de se répandre.

Et à l'encontre d'autres instruments de microanalyse, ces tests fonctionnent sans l'aide de pompes pour propulser les liquides dans les microcanaux.

Des tests médicaux pour le monde en développement
En fabriquant des instruments d'analyse microfluidique à base de papier, l'objectif des chercheurs était de produire des épreuves diagnostiques peu coûteuses en utilisant « une technologie particulièrement appropriée aux besoins des pays en développement », a dit à America.gov Andres Martinez, le doctorant qui a aidé à mettre au point le test micropapier et l'auteur de l'étude sur le sujet.

Selon M. Martinez, le papier possède de nombreux avantages dans les instruments de microanalyse.

Le papier est fin et léger, ce qui facilite le transport de nombreuses trousses d'essais vers les régions reculées. Le papier est également inflammable, permettant l'incinération des tests utilisés comme moyen de prévenir les contaminations par le biais de liquides organiques. Enfin, l'abondance de papier fait qu'il sera un jour possible de fabriquer des instruments de diagnostic de ce type localement.

Dans l'avenir, la technologie de fabrication du papier, telle qu'elle s'applique par exemple dans le secteur de l'imprimerie, pourrait être adaptée à la production d'instruments diagnostiques à grande échelle, a ajouté M. Martinez.

Ce dernier œuvre actuellement pour adapter le micropapier à l'analyse du sang, un liquide plus complexe que l'urine, dans le but de mettre au point un test pour détecter l'insuffisance hépatique. Il s'agit, donc, d'adapter le test pour que pouvoir détecter les niveaux élevés d'enzymes dans le sang, une caractéristique de l'insuffisance hépatique.

Toutefois, il n'est pas possible de tester le sang (entier) tel quel. Il faut d'abord retirer les globules rouges, ne laissant que le plasma. Se fondant sur des travaux (de laboratoire) précédents, M. Martinez envisage d'utiliser un fouet à œufs comme centrifugeuse pour séparer le plasma des autres éléments sanguins, puis de l'appliquer sur un micro papier pour détecter les niveaux d'enzymes hépatiques.

De nombreux médicaments ont des effets secondaires néfastes sur le foie, mais il n'y a pas, actuellement, de moyen rapide, fiable et peu coûteux pour évaluer la fonction hépatique chez les malades sur le terrain, a dit M. Martinez. Il espère qu'il sera possible d'utiliser les tests sur micropapier pour détecter les infections microbiennes et virales dans le sang.
Diagnostics pour tous

Pour produire et distribuer, à grande échelle, les tests micropapier, M. Whitesides et ses collègues ont formé Diagnostics pour tous, une société à but non lucratif. Lancée par Hayat Sindi, une scientifique d'Arabie saoudite en visite aux États-Unis, Diagnostics pour tous a pour but d'offrir à la communauté médicale internationale des moyens de diagnostics à la portée des ressources financières de tous.

Mme Sindi, qui a aidé à fonder cette organisation, a participé à la rédaction du plan d'affaires, lequel a remporté plusieurs prix, notamment les prestigieux Prix de 100.000 dollars du concours d'affaires de l'Institut de technologie du Massachusetts et celui du concours de l'école d'affaires de l'université Harvard.

La société Diagnostics pour tous a battu plus de 230 autres équipes concurrentes, à la fois à but lucratif et non lucratif, pour gagner la compétition de l'Institut de technologie du Massachusetts et le prix de 100.000 dollars, en mai, la première fois qu'une société à but non lucratif remporte cette victoire.
http://www.america.gov/st/health-french/2008/December/20081215154019adkcilerog0.1331446.html

Pour ses 120 ans, la Tour Eiffel se refait une beauté

Conformément aux instructions de son fondateur Gustave Eiffel, elle se fait ravaler la façade tous les sept ans.

Les 25 peintres de la Stelma, une société grecque implantée à Saint-Nazaire en France, n'ont pas le vertige. Normal, puisque ce sont eux qui vont partir à l'assaut de la Tour Eiffel, pour lui refaire une beauté. Depuis qu'en 1968 la dame de fer a revêtu cette couleur «brun Tour Eiffel», après avoir expérimenté le brun rouge, l'ocre brun, le jaune brun et le rouge brun, elle n'en a plus changé. Et selon Jean Bernard Bros, président de la Société d’Exploitation De La Tour Eiffel, c'est le brun tout simple "qui lui va le mieux» et «les cinéastes, photographes, amoureux de Paris, Parisiens et Parisiennes disent aimer cette couleur depuis 40 ans».
Cette couleur est dégradée en trois tons qui vont du plus foncé en bas au plus clair en haut pour que vue du sol, la Tour Eiffel soit en harmonie avec le ciel parisien. Mais entre la rouille, les déjections d’oiseau et la pollution, il faut la repeindre tous les 7 ans. Ainsi, les peintres, souvent des alpinistes aguerris, revêtent leur harnais et attachent leurs pinceaux et brosses à leur bras pour éviter toute chute.
Et c'est parti pour un grand nettoyage qui dure 15 à 18 mois et nécessite 60 tonnes de peinture, désormais entièrement écolo. Toutefois, la Tour Eiffel ne ferme pas durant son toilettage et reste ouverte 365 jours par an, pour permettre à ses 6 millions de visiteurs de profiter de la vue sur Paris...
Mercredi 1er avril 2009