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rasha kamel
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"Now scientists at MIT and the City College of New York have achieved that feat, imaging excitons' motions directly. This could enable research leading to significant advances in electronics, they say, as well as a better understanding of natural energy-transfer processes, such as photosynthesis.
The research is described this week in the journal Nature Communications, in a paper co-authored by MIT postdocs Gleb Akselrod and Parag Deotare, professors Vladimir Bulovic and Marc Baldo, and four others.
"This is the first direct observation of exciton diffusion processes," Bulovic says, "showing that crystal structure can dramatically affect the diffusion process."
"Excitons are at the heart of devices that are relevant to modern technology," Akselrod explains: The particles determine how energy moves at the nanoscale. "The efficiency of devices such as photovoltaics and LEDs depends on how well excitons move within the material," he adds.
An exciton, which travels through matter as though it were a particle, pairs an electron, which carries a negative charge, with a place where an electron has been removed, known as a hole. Overall, it has a neutral charge, but it can carry energy. For example, in a solar cell, an incoming photon may strike an electron, kicking it to a higher energy level. That higher energy is propagated through the material as an exciton: The particles themselves don't move, but the boosted energy gets passed along from one to another.
While it was previously possible to determine how fast, on average, excitons could move between two points, "we really didn't have any information about how they got there," Akselrod says. Such information is essential to understanding which aspects of a material's structure—for example, the degree of molecular order or disorder—might facilitate or slow that motion".
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rasha kamel

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"Like animals, plants have hormones that send chemical signals between its cells relaying information about the plant's development or interactions with the outside world. One particular way in which plants use hormone signals is in reaction to drought or soil saltiness. The hormone responsible for this type of response is called abscisic acid. It not only controls efficient water use, but plays a role in signaling when seeds should remain dormant and when they should germinate, depending on soil conditions.
New work from a team including Carnegie's Wolf Frommer will allow researchers, for the first time, to measure the levels of abscisic acid in individual plant cells in real time. It is published in eLife.
"This will vastly improve our understanding of how abscisic acid works in a plant that is stressed by salt or lack of water," Frommer explained. "This new tool can help engineers and farmers work to increase crop yields, which is especially important as climate change puts plants under increased stress."
The team's tool uses multiple fluorescently tagged proteins to measure the concentration of abscisic acid found in a plant cell. Their findings indicate that there are likely more proteins responsible for transporting abscisic acid into a cell than are currently known and also that abscisic acid is eliminated by root cells very quickly after uptake".
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"A Tyrannosaurus rex baring banana-sized teeth is taking over Washington, D.C.—and it came via FedEx. The 12-meter “Nation’s T. rex” arrived this morning at the Smithsonian Institution’s National Museum of Natural History accompanied by a police escort and was greeted by a packed hall of reporters and dinosaur lovers. The 66-million-year-old bipedal dinosaur, uncovered in 1990, journeyed 3200 kilometers from its former home in Bozeman, Montana, in a dino-decorated delivery truck complete with its own tracking number. “I’m happy to say we FexExed the T. rex,” joked museum director Kirk Johnson before signing a 50-year loan agreement with the U.S. Army Corps of Engineers, the fossil’s former caretaker.
The 7-ton dinosaur, one of the five most complete specimens ever unearthed, will become the centerpiece of the museum’s $48 million renovated National Fossil Hall, scheduled to debut in 2019. The hall will be named in recognition of David Koch, executive vice president of Koch Industries Inc., who donated $35 million toward the makeover. The museum currently displays a replica skeleton erected shortly after the Smithsonian’s failed 1999 bid for the famous T. rex nicknamed “Sue.” Until National Fossil Day on 15 October, visitors can watch museum staff unpack, catalog, and 3D scan the fossilized bones in a “Rex Room” exhibit. The bones will then be shipped to Toronto for mounting".
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"If an insect drew a line as it chased its next meal, the resulting pattern would be a tangled mess. But there’s method to that mess: It turns out the tiger beetle, known for its speed and agility, does an optimal reorientation dance as it chases its prey at blinding speeds".
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"Computer scientists, mathematicians and geophysicists have optimized the SeisSol earthquake simulation software on the SuperMUC high performance computer to push its performance beyond the 'magical' one petaflops mark -- one quadrillion floating point operations per second".
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"Photosynthesis provides fixed carbon and energy for nearly all life on Earth, yet many aspects of this fascinating process remain mysterious. We do not know the full list of the parts of the molecular machines that perform photosynthesis in any organism. A team developed a highly sophisticated tool that will transform the work of plant geneticists on this subject".
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rasha kamel

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"Metals and organic molecules can combine to form coordination compounds whose structure and properties depend on the components. Examples from nature include the oxygen-binding heme groups in our red blood cells with their central iron atom or the magnesium complex at the heart of photosynthesis. Scientists have also explored the use of these types of compounds to build things, such as networked scaffold structures. A team from the University of Melbourne, the Baker IDI Heart and Diabetes Institute (Melbourne, Australia), and the University Medical Center Freiburg (Germany), is particularly interested in structures in the form of hollow capsules. Led by Frank Caruso, these researchers haven now been able to demonstrate that a single organic ligand, tannic acid, can coordinate to 18 different metals to form capsules made of metal–phenolic networks (MPNs). The metals are aluminum, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, molybdenum, ruthenium, rhodium, cadmium, cerium, europium, gadolinium, and terbium.
The production method is simple: just mix tannic acid with a solution of the desired metal ion in the presence of a suitable substrate—in this case microparticles. Removal of the substrate leaves behind hollow microcapsules.
The properties of the capsules depend on the type and number of metal ions. For example, capsules with aluminum have a property profile suitable for drug transport: while they are relatively stable at pH values typical of blood, they come apart at the lower pH values found in some cell compartments. They could thus be used to transport a drug though the blood and release it after entering a cell".
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"(The eggshell is not like any other we have seen before. It looks like a tiny asteroid field,) says UA visiting assistant professor Liliana D'Alba, describing what she and her research colleagues discovered when they examined the eggshell surface with a scanning electron microscope.
After testing the brush-turkey egg white, an important line of defense against infections, the scientists found its antimicrobial function to be no more exceptional than that of other bird eggs. They then examined the brush-turkey eggshell to find out if the nanoparticles shielded bacteria. Since water provides a breeding ground for bacteria, the researchers applied water to the eggshell to determine its hydrophobicity, or water repellency. Like water on a freshly polished car, water on the brush-turkey egg beaded up.
"Most bacteria grow best when water is available, and these eggs appear to reduce water on their surface," D'Alba says, noting that conversely, water spreads across the shell surface of eggs without nanospheres, such as chicken eggs".
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"Researchers have uncovered clues to how past peoples moved across their landscape as the once lush environment deteriorated. Scientists sampled bone and teeth enamel, and used their chemical signatures to determine individuals' origins, as well as where they resided during the course of their lives. The results suggest that individuals chose different mobility strategies but that near the end of the lake area's occupation, as their environment dried out, Saharan peoples became more mobile".
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"The intestinal bacteria of present-day hunter-gatherers has for the first time been deciphered by an international team of researchers. Bacterial populations have co-evolved with humans over millions of years, and have the potential to help us adapt to new environments and foods. Studies of the Hadza offer an especially rare opportunity for scientists to learn how humans survive by hunting and gathering, in the same environment and using similar foods as our ancestors did".
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Have her in circles
17,353 people
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Introduction
I had PhD in computational chemistry
I am working in archaeological analysis
I am interesting in geology, material science
and environmental sciences