Archive for 1月 2018

Home Archive for 1月 2018

軟木橡樹 Cork oak - Quercus suber

在數千年以前，羅馬人發現，它會漂浮，用於製作漁網浮標及涼鞋。

現今，軟木橡樹是製作葡萄酒瓶塞原料主要來源，原生於歐洲西南部和非洲西北部，海拔300至500公尺的地方，樹高約20公尺，與其它橡樹不同，軟木橡樹是常綠的，葉子是不會掉落。

為什麼軟木橡樹有這麼厚的樹皮，因為林森火災發生時，厚的樹皮可以隔熱保護樹不致於被燒死，枝條可以迅速再生，來填補空缺的樹冠。在地中海火生態系統中獲得了生存勝利。

樹齡達到25年後，每隔9至12年就可以可收穫一次，收割軟木完全依靠人工。因取樹皮而不傷害樹木需要一些技術，收割人員需要培訓。一棵軟木橡樹在200年種植過程可以收穫約12次。每年可以生產 30萬噸，產值15億歐元，3萬人以此維生。

資料來源:

https://www.facebook.com/Seminisia/posts/1840707159334951

Quercus suber, commonly called the cork oak, is a medium-sized, evergreen oak tree in the section Quercus sect. Cerris. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores of cricket balls. It is native to southwest Europe and northwest Africa. In the Mediterranean basin the tree is an ancient species with fossil remnants dating back to the Tertiary period. The cork oak forest is one of the major plant communities of the Mediterranean woodlands and forests eco-region. Cork oak grows best in areas with cold, moist winters and hot summers. It is commonly found at 300-600 m, but can occur up to 1,000 m above sea level.

Cork oak bark has been harvested for thousands of years, and with good reason. The Romans discovered that it would float and used it for buoys in fishing nets, as well as for making sandals. Today, the main uses of cork are in the production of wine bottle stoppers and insulation material. From medieval times cork has been used to insulate buildings, keeping heat in during the winter and keeping it out during the summer. Monasteries were sometimes built with cork oak to protect them from the heat of the summer sun

Quercus suber is slow-growing and long-lived, some individuals surviving to 250 years of age. Cork oak landscapes are mosaics of forest habitats, comprising cork, holm and deciduous oak species, stone and maritime pines, wild olive trees, maquis (a type of Mediterranean shrubland), and pasture. Cork oak is an evergreen tree with low, twisted branches and downy twigs. It can grow up to 20 m high, but it is typically more stunted in its native environment. It has very thick and deeply ridged bark, which is harvested as cork. The green leaves are 4-7 cm long, with spiny-ended lobes. and their margins are often curved downwards. The leaves fall during the second year of growth. Once a year, the tree produces fruits, known as acorns. The acorns are 2-3 cm long, and sit in a deep cup fringed with elongated scales. Cork oak is wind pollinated and monoecious (having separate male and female flowers on the same plant). As with other oaks, the seed of Quercus suber should be collected in the autumn when green. The viability of acorns can decline very quickly. In the glasshouse, seeds germinate after around 6-8 weeks, whilst those in the field do not germinate until the following spring.

The tree forms a thick, rugged bark containing high levels of suberin. Over time the cork cambium layer of bark can develop considerable thickness and can be harvested every 7 to ten years to produce cork. The harvesting of cork does not harm the tree, in fact, no trees are cut down during the harvesting process. Only the bark is extracted, and a new layer of cork regrows, making it a renewable resource.

As a pyrophyte, this tree has a thick, insulating bark that makes it well adapted to forest fires. After a fire, many tree species regenerate from seeds (as, for example, the maritime pine) or resprout from the base of the tree (as, for example, the holm oak). The bark of the cork oak allows it to survive fires and then simply regrow branches to fill out the canopy. The quick regeneration of this oak makes it successful in the fire-adapted ecosystems of the Mediterranean biome.

Virgin cork (or 'male' cork) is the first cork cut from generally 25-year-old trees. Another 9 to 12 years is required for the second harvest, and a tree can be harvested about 12 times in its lifetime. It is obtained by peeling the bark away from the trunk, leaving a thin layer of new cork still covering the functional part (secondary phloem) of the trunk. Cork harvesting is done entirely without machinery, being dependent solely on human labor. Usually five people are required to harvest the tree's bark, using a small axe. The process requires training due to the skill required to harvest bark without harming the tree. The European cork industry produces 300,000 tonnes of cork a year, with a value of €1.5 billion and employing 30,000 people. Wine corks represent 15% of cork usage by weight but 66% of revenues.

The cork left after stoppers have been made is used to make a wide range of products, including insulation panels, floor and wall tiles and sound-proofing in the car industry, as well as for handicrafts and artistic uses. This include cork paper, used in printing, book covering, clothing manufacture, cork maroquinerie and other products. Cork is also used in making cricket balls, badminton shuttlecocks, handles of fishing rods and special devices for the space industry.

The habitats that support cork oak are under ever-increasing threat, mainly due to human activity such as the intensification of agriculture and careless causes of forest fires (too frequent fires can damage the trees, as it makes them susceptible to fungal infection).

The increasing use of plastic wine stoppers and metal screw tops could reduce the value of cork oak forests, leading to their conversion or abandonment. WWF has been working to publicise the environmental and economic value of cork stoppers, in particular with the wine industry, to show what would be lost if cork forests disappeared, and has a major programme to promote products derived from sustainably managed cork oak forests.

Sources:

https://en.wikipedia.org/wiki/Quercus_suber

http://powo.science.kew.org/…/urn:lsid:ipni.org:names:29678…

https://www.rainforest-alliance.org/species/cork-oak

https://upload.wikimedia.org/…/7f/Cork_oak_trunk_section.jpg

https://selectree.calpoly.edu/…/ori…/quercus-suber-fruit.jpg

https://i.pinimg.com/…/27/66ae273484d64303bb8829af5e764acb.…

http://www2.palomar.edu/users/warmstrong/images/acorn4.jpg

https://www.uv.es/jgpausas/sp/Quercus-suber_harvesting.jpg

https://www.rainforest-alliance.org/species/cork-oak

植物紋身傳感器 plant tattoo sensors

美國愛荷華州立大學的研究人員已經開發出這些“植物紋身傳感器”，可以及時直接測量農作物的用水量。這些是傳感材料是以石墨烯做出來的，怎麼有點像蕨類孢子

Engineers make wearable sensors for plants, enabling measurements of water use in crops

Iowa State University plant scientist Patrick Schnable quickly described how he measured the time it takes for two kinds of corn plants to move water from their roots, to their lower leaves and then to their upper leaves.

This was no technical, precise, poster talk. This was a researcher interested in working with new, low-cost, easily produced, graphene-based, sensors-on-tape that can be attached to plants and can provide new kinds of data to researchers and farmers.

"With a tool like this, we can begin to breed plants that are more efficient in using water," he said. "That's exciting. We couldn't do this before. But, once we can measure something, we can begin to understand it."

The tool making these water measurements possible is a tiny graphene sensor that can be taped to plants - researchers have dubbed it a "plant tattoo sensor." Graphene is a wonder material. It's a carbon honeycomb just an atom thick, it's great at conducting electricity and heat, and it's strong and stable. The graphene-on-tape technology in this study has also been used to produce wearable strain and pressure sensors, including sensors built into a "smart glove" that measures hand movements.

Researchers describe the various sensors and the "simple and versatile method for patterning and transferring graphene-based nanomaterials" to create the flexible sensors in a paper featured on the cover of the December 2017 issue of the journal Advanced Materials Technologies.

The research has been primarily supported by the Faculty Scholars Program of Iowa State's Plant Sciences Institute.

Liang Dong, an Iowa State associate professor of electrical and computer engineering, is the lead author of the paper and developer of the technology. Seval Oren, a doctoral student in electrical and computer engineering, is a co-author who helped develop the sensor-fabrication technology. Co-authors who helped test applications of the sensors are Schnable, director of Iowa State's Plant Sciences Institute, a Charles F. Curtiss Distinguished Professor in Agriculture and Life Sciences, the Iowa Corn Promotion Board Endowed Chair in Genetics and the Baker Scholar of Agricultural Entrepreneurship; and Halil Ceylan, a professor of civil, construction and environmental engineering.

"We're trying to make sensors that are cheaper and still high performing," Dong said.

To do that, the researchers have developed a process for fabricating intricate graphene patterns on tape. Dong said the first step is creating indented patterns on the surface of a polymer block, either with a molding process or with 3-D printing. Engineers apply a liquid graphene solution to the block, filling the indented patterns. They use tape to remove the excess graphene. Then they take another strip of tape to pull away the graphene patterns, creating a sensor on the tape.

The process can produce precise patterns as small as 5 millionths of a meter wide - just a twentieth of the diameter of the average human hair. Dong said making the patterns so small increases the sensitivity of the sensors.

(The process, for example, produced a detailed image of Iowa State's Cyclone mascot that was less than 2 millimeters across. "I think this is probably the smallest Cyclone," Dong said.)

"This fabrication process is very simple," Dong said. "You just use tape to manufacture these sensors. The cost is just cents."

In the case of plant studies, the sensors are made with graphene oxide, a material very sensitive to water vapor. The presence of water vapor changes the conductivity of the material, and that can be quantified to accurately measure transpiration (the release of water vapor) from a leaf.

The plant sensors have been successfully tested in lab and pilot field experiments, Dong said.

A new three-year, $472,363 grant from the U.S. Department of Agriculture's Agriculture and Food Research Initiative will support more field testing of water transport in corn plants. Michael Castellano, an Iowa State associate professor of agronomy and William T. Frankenberger Professor in Soil Science, will lead the project. Co-investigators include Dong and Schnable.

The Iowa State University Research Foundation has applied for a patent on the sensor technology. The research foundation has also granted an option to commercialize the technology to EnGeniousAg - an Ames startup company co-founded by Dong, Schnable, Castellano and James Schnable, an assistant professor of agronomy and horticulture at the University of Nebraska-Lincoln, a collaborator on another Iowa State sensor project that sparked establishment of the company (and Patrick Schnable's son).

"The most exciting application of the tape-based sensors we've tested so far is the plant sensor," Dong said. "The concept of wearable electronic sensors for plants is brand new. And the plant sensors are so tiny they can detect transpiration from plants, but they won't affect plant growth or crop production."

But that's not all the sensors can do. The technology could "open a new route" for a wide variety of applications, the authors wrote in their paper, including sensors for biomedical diagnostics, for checking the structural integrity of buildings, for monitoring the environment and, after appropriate modifications, for testing crops for diseases or pesticides.

資料來源:

https://phys.org/news/2018-01-wearable-sensors-enabling-crops.html