Prime Minister Stephen Harper announced regulatory approval for CNOOC's $15.1 billion takeover of oil and gas company Nexen, and Petronas' offer for Canadian gas producer Progress Energy Resources, estimated at $5.5 billion.
However, he cautioned that Ottawa would henceforth block attempts by foreign state-owned companies to buy controlling stakes in Canada's lucrative oil sands.
"In light of growing trends and following the decisions made today, the government of Canada has determined that foreign state control of oil sands development has reached the point at which further such foreign state control would not be of net benefit to Canada," Harper told a press conference.
"The larger purposes of state-owned enterprises may go well beyond the commercial objectives of privately owned companies," he said.
"It is not an outcome any responsible government of Canada could ever allow to happen. We certainly will not."
Harper however held open the door for "exceptional circumstances" when the new rule may not be applied.
In a statement, Industry Canada -- the government's economic development and corporate affairs department -- said Ottawa will progressively increase the review threshold for deals to CAN$1 billion (US$1.01 billion).
The industry minister will continue to review state-owned bids for Canadian companies in non-energy sectors when valued at CAN$330 million or more, it said.
The CNOOC takeover of Nexen comes seven years after political panic about China's thirst for global energy assets scuppered a massive bid to take over California's Unocal.
It is China's largest foreign investment and its largest energy deal, according to data firm Dealogic. And it too stirred strong opposition across Canada.
Calgary-based Nexen produces the equivalent of around 213,000 barrels of oil a day, with concessions in Canada's oil sands, Britain's North Sea, Nigeria, the Gulf of Mexico and Colombia.
China is the biggest energy consumer in the world, the second biggest consumer of oil and has been snapping up resource assets across the globe in order to fuel break-neck growth.
CNOOC already has CAN$2.8 billion invested in Canada, including stakes in MEG Energy Inc. and oil sands producer OPTI Canada Inc.
The company pledged in its proposal to keep Nexen's regional headquarters in Calgary and proposed that Nexen assume management duties for existing CNOOC operations in North America and the Caribbean.
Nexen's assets in Britain, the United States and other countries would continue to be managed from regional offices, and CNOOC would retain the current management, employees and local suppliers in those operations.
As for the Progress Energy deal, an earlier acquisition proposal by Petronas, aimed at securing stable supplies of liquefied natural gas (LNG) from North America, was rejected by the Canadian industry minister.
Last year, Petronas established a joint venture with Progress Energy to develop a portion of the Canadian company's shale assets and an integrated LNG export facility in western Canada.
The Malaysian giant this week sweetened its bid by offering to boost the Canadian terminal's capacity by 60 percent.
There is growing demand for LNG in Asia's energy-hungry economies, especially in Japan, where power firms have had to step up conventional electricity generation with the country's nuclear plants shut down.
Teaching Computer Science (CS) is one way to help students of all ages to learn more about systems thinking, creative problem solving, design, art and aesthetics, writing and storytelling, and other 21st century skills. This article includes 12 resources (curriculum guides, lesson plans, student activities and games, programming apps and tools) to help any K-12 teacher get started teaching computer science concepts and programming to their students.
K-12 Computer Science Curriculum and Resources
Below are resources to help get you started with teaching computer science to your students.
A Model Curriculum for K?12 Computer Science
The Association for Computing Machinery (ACM) put together a model curriculum for teaching computer science in K-12. According to the ACM, ?Computer science (CS) is the study of computers and algorithmic processes1, including their principles, their hardware and software designs, their applications, and their impact on society.?
This report proposes a model curriculum that can be used to integrate computer science fluency and competency throughout primary and secondary schools, both in the United States and throughout the world. It is written in response to the pressing need to provide academic coherence to the rapid growth of computing and technology in the modern world, alongside the need for an educated public that can utilize that technology most effectively to the benefit of humankind.
Computing and Programming Experience (CAPE)
We now face a new and deep Digital Divide, where students know how to consume technology while others are creating the technologies that will shape our future. It is time to bridge this divide by supporting access to curriculum and educational technology for all students, leveling the playing field so that students and educators alike have the opportunity to shape the worlds of their future. The creators of tomorrow?s innovations are everywhere, ready to be engaged and inspired. This reality led us to create Google?s Computing and Programming Experience (CAPE), a multi-week summer program located in Google offices across the US, designed to inspire excitement about computer science for incoming 9th grade (graduating 8th grade) students.
Exploring Computational Thinking
Computational thinking (CT) involves a set of problem-solving skills and techniques that software engineers use to write programs that underlie the computer applications you use such as search, email, and maps. Here are specific techniques. There is a hypothesis that CT is a critical skill for 21st-century students. The hypothesis states that not only is this skill critical for our students and ultimately our population to use computing and technology effectively, CT also supports and enhances the learning of more traditional curriculum. In the 21st century, our students need to develop CT skills, along with ?reading, writing and arithmetic.?
CS Unplugged: Computer Science? without a Computer!
CS Unplugged is a collection of free learning activities that teach Computer Science through engaging games and puzzles that use cards, string, crayons and lots of running around. The activities introduce students to underlying concepts such as binary numbers, algorithms and data compression, separated from the distractions and technical details we usually see with computers. CS Unplugged is suitable for people of all ages, from elementary school to seniors, and from many countries and backgrounds.
Apps and Tools for Programming in K-12
Below are several apps and tools that students in elementary, middle, or high school could use to program apps, games, simulations, and so on. Most of the apps work on an iPad or Android device and are free or inexpensive ways to get kids excited about programming.
Scratch
Scratch is a programming language that makes it easy to create interactive art, stories, simulations, and games ? and share those creations online. ScratchEd is an online community where Scratch educators:
Share Stories
Exchange Resources
Ask Questions
Find People
Bootstrap World
Bootstrap World is a FREE curriculum for students ages 12-16, which teaches them to program their own videogames using purely algebraic and geometric concepts.?Our mission is to use students? excitement and confidence around gaming to directly apply algebra to create something cool.
App Inventor
App Inventor is a great tool to teach programming to high school students. Google Intern, Michelle Hutton, created the following 6 week curriculum. This curriculum is a project based curriculum that allows students to explore the world of computer science through the creation of smartphone apps.
Gamestar Mechanic
Gamestar Mechanic is a game and online community that teaches kids how to design their own games! Designing games builds:
Systems Thinking,
21st Century Skills,
Creative Problem Solving,
Art and Aesthetics,
Writing and Storytelling,
and creates a motivation for STEM learning.
Microworlds
MicroWorlds EX is an environment in which students can explore and test their ideas as they create science simulations, mathematical experiments, interactive multimedia stories, whatever they can imagine!
RunRev
With RunRev, you can create Apps for the iPhone, iPad, Android Phones, Android Tablets and Desktops. You can create any type of App you like ? for example, a game, simulation, utility, business or social App. Our English-like language is designed to be as close as possible to the way you speak. This means students can quickly understand the programs they write.
Codea
Codea for iPad lets you create games and simulations ? or just about any visual idea you have. Turn your thoughts into interactive creations that make use of iPad features like Multi-Touch and the accelerometer.
Sketch Nation
Use Sketch Nation to create your own games simply by drawing on a piece of paper and taking a picture of your drawing with the iPhone camera.
Tagged as: 21st Century Skills, Computer Science in K-12
BEIRUT (AP) ? Syrian rebels fighting to topple President Bashar Assad declared Damascus International Airport a "legitimate target" Friday in a bid to cut off regime supplies, as clashes between government troops and rebels forced the closure of the airport road for the second time this week.
Fighting around the Syrian capital and the airport has intensified in recent days as rebels press a battle they hope will lead to the collapse of Assad's regime after 20 months of conflict. They have set their sights on the city of 1.7 million, and fighting on the outskirts is raising fears that it soon could be facing the most brutal battle of the Syrian civil war.
The rebels issued a stern warning to the regime and travelers planning to use the country's main airport, just a few kilometers (miles) south of the capital. Loss of control of the airport would be a major blow to the regime.
A fighter who is part of the push against the airport declared it a legitimate target, claiming that the regime has stationed troops and elite forces in it as well as military planes that transport ammunition.
The clashes already have forced the suspension of commercial flights over the past week, although airport officials said Friday the facility was still functioning.
Rebels said they were trying to cut military supplies to the government. Iran and Russia are widely believed to be supplying it with weapons through the airport. Over the past months, Turkey and Iraq stopped several planes coming from those two countries that were headed to Damascus and searched them.
"This would send a very strong political message to the regime, it will be a moral victory, to say the least," said the fighter, who gave only his first name, Nour, for security reasons. "The battle to cut off the regime supplies from the airport has started."
Another rebel, speaking on condition of anonymity for the same reason, said the airport is now considered a "military zone."
"We urge civilians to stay away," said the rebel, a member of the Damascus area military command involved in Friday's fighting.
An airport official said the highway leading to the facility was closed Friday because of the fighting. The officials said, however, that the airport was functioning as normal and that people were reaching it through side roads.
The official declined to be identified because he was not authorized to give official statements.
The fresh violence around the capital comes amid growing international concerns that Assad was preparing to use chemical weapons as an act of desperation.
Syria has not confirmed it has non-conventional weapons, and insists it would never use such arms against its own people. U.S. officials say intelligence suggests the government does have the weapons, and has moved some of its stockpiles in recent days.
Also on Friday, U.N. Secretary-General Ban Ki-moon renewed a call for Syria to not use chemical weapons, saying the move would amount to an "outrageous crime" against humanity.
Speaking to reporters after visiting Syrian refugee camps in Jordan and Turkey, he also called for an end to the violence.
"The slaughter in Syria must stop. The military path is a dead end. It only fills the streets with more blood," he told reporters in Turkey.
Ahmet Uzumcu, director-general of the Organization for the Prohibition of Chemical Weapons, said Friday he had written to Syria's foreign minister urging his government to ban the use of chemical weapons by signing on to the current international convention "without delay."
Syrian opposition leaders said they were concerned the government would use its chemical weapons. George Sabra, head of the Syrian National Council opposition group, called on Syrian soldiers to ignore any orders to use them.
"Any civilian or military Syrian, who implements or helps implement this crime will be held accountable as a traitor for this country and will be pursued on charges of committing genocide," he said at a press conference in Paris.
"The Syrian people will not forgive or have mercy on anyone who orders the use of weapons of destruction and anyone who participates in executing this crime," he added.
Syrian activists said government forces were firing rockets and mortars at suburbs south of Damascus Friday amid heavy clashes with rebels. Most of the fighting was taking place in the towns of Aqraba and Beit Saham near the airport.
In other violence, a car bomb exploded in the government controlled Inshaat neighborhood in the central Homs province, setting cars on fire and covering the streets with debris, activists said.
An amateur video showed Syrian soldiers rushing to the scene as people cried in shock. It was not immediately clear what the target was.
___
Associated Press writers Albert Aji in Damascus, Suzan Fraser in Ankara and Mike Corder in the Netherlands contributed to this report.
Pizza Hut is releasing a new limited-edition fragrance, which started out as a joke on a Canada Facebook page. This perfume bottle is very real and the product sounds interesting. Why not? White Castle has ?burger candles? with a scent.
Grip Limited, an advertising firm that works with Pizza Hut Canada, originally floated the tongue-in-cheek notion on the Pizza Hut Canada Facebook page back in August as part of a broader push to promote more engaging social media activity.
The post asked fans to dream up names for an imaginary scent inspired by ?the smell of a box of Pizza Hut pizza being opened.? But the fan response to the idea was so enthusiastic that Grip and Pizza Hut decided to make the perfume a reality.
A month and a half later, to commemorate the fact that Pizza Hut Canada had gotten 100,000 fans, the chain?s community managers announced that the first 100 people to message them would actually get a bottle of Pizza Hut perfume. And sure enough, the bottles were shipped to those 100 lucky fans at the beginning of December.
Pizza Hut Canada has not announced any plans to make more of the perfume in the future. But you can be sure we?re going to keep our eyes peeled (zing!) for any secondhand bottles of the scent so we can get a slice (zing zing!) of the action.
This is one example how a big franchise like Pizza Hut is using social media to launch a viral campaign. Will it sell pizzas? It might, but it could mean other companies might join the frenzy.
Last Friday I learned I?ll soon be writing a second book for a traditional publisher. I couldn?t feel more proud and excited. And I couldn?t feel more afraid and overwhelmed about being a multiple-book author.
I probably have about seven or eight books I want to write and publish. Not all of them will end up with traditional publishers. Like the 10 short books I?ve already self-published, many of them will appear under my own imprint, I?m sure. And while no one else pushes me to write and publish all these books, I do.
Why Write More Than One Book
Here?s a fact you should know: The more books you sell, the more books you sell. That means the more books you write and publish, the more books you sell.
With each new book, you gain more readers. Those readers might also decide to purchase your other books if they like the first book they read. You also become a better writer, learn more about what it takes to become a successful author and increase your expert status. All of these factors add up to more book sales and a more rewarding career for you as a writer.
That?s why it?s important to consider becoming a multiple-book author. It?s also why most nonfiction book proposals include a Spin-Offs section. In this section you describe several additional books you want to write. This proves to the publisher you are not just a one-book wonder. Publishers want to invest in an author long-term; they want good publishing partners.
What it Takes to Write Multiple Books
I have to admit that the I never put a lot of effort into marketing my self-published books. They were primarily created to help me build platform as a speaker. I need a book to say I was an author and to get more speaking gigs. (However, they sell better today because of my traditionally published book.) Because a traditional publisher had invested in me and I made promises about the book, I felt the need to do more promotion?and to sell books. I had to live up to my commitments. That meant I had to do a lot of work in addition to or besides writing.
Many writers say they want to write a book a year?and some do. Many, like me, have written multiple books. Doing this is not as easy as it sounds (or maybe it doesn?t sound easy to you). Here?s what I think it takes:
Determination: You must be determined to achieve your goals and to fulfill your purpose as a writer and an author.
Commitment: You must commit to your goals, purpose and path as a writer or author, just like you would commit to a marriage partner.
Perseverance: You must be willing to persevere despite difficulties, obstacles, or discouragement?no matter. And that means no excuses.
(I wrote about this more extensively here.)
You also have to be able to move through common issues that arise as you find yourself with more than one book to write and promote at any given time.
Overwhelm: It can feel like too much, but know you can ask for and receive (pay for) help. Remind yourself you are creating the life of a writer and author.
Fear: Fear of success as well as fear of failure can stop you in your tracks?even cause writer?s block. You need to constantly remind yourself of why you write and take baby steps forward. Remind yourself, ?I can do this. I must do this.?
Hard Work: Sometimes it will feel too hard. I have days when I work so long?(you don?t even want to know), but the fact that people read my blogs and buy my books, that my book has remained an Amazon bestseller for 29 weeks and that a publisher is about to contract me to write another book makes it worthwhile. (So does seeing a video like this ones in which someone features my book! Pay attention to the books on the desk and the one Don Power picks up.)
Plus, remember that at the end of the day, knowing your books (plural) are out of your head and in the hands of readers?or at least available for purchase?leads to an important aspect of being a writer and author: fulfillment.?I can?t tell you how fulfilling it is to write and publish multiple books (and, yes, in multiple genres).? In this way I truly fulfill my purpose and my potential as an author.
And don?t let anyone tell you you can?t write a book a year?or shouldn?t?or more than a book a year. I say, write as many books in a year as you feel inspired to write. Just be aware of what it takes?and prepared?to be a multiple-book author.
Tell me: Do you plan on becoming a multiple-book author or are you one already? What?s your experience or thoughts on this writing path?
Photo courtesy of microsoftclipart.com
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Are You a One Book Author?
Beyond Books: Building Multiple Streams of Income
Why You Need a New Hat and Glass to Become an Author
25 Ways to Begin a Career as a Writer or Author
Julien Smith on Methods for Becoming a Bestselling Author
A 12-year-old future critic was watching the premiere airing and echoed that assessment.
Animated Christmas specials have become as much a part of our holiday traditions as decked halls, nogged egg and jingled bells. The first aired 50 years ago this month.
That was four years before the Grinch first tried to steal Christmas with the help of narrator Boris Karloff. That was three years before a depressed Charlie Brown learned the true meaning of Christmas with the help of little Linus and a tiny needle-shedding tree. That was two years before a stop-motion puppet version of Santa drove through a foggy Christmas Eve with the help of Rudolph and his nose so bright.
The animated special that started it all was aired by NBC at 7:30 p.m. Dec. 18, 1962. A musical version of Charles Dickens? beloved 1843 tale about miserly Ebenezer Scrooge, it was called ?Mr. Magoo?s Christmas Carol.?
?Few people realize how incredibly influential it was,? said animation director-producer Darrell Van Citters, author of the 2009 book ?Mr. Magoo?s Christmas Carol: The Making of the First Animated Christmas Special? (Oxberry Press). ?It showed that an animated special could be commercially and critically successful. It unquestionably paved the way for Rudolph, Charlie Brown and the Grinch.?
The reviews were ecstatic in 1962. Many critics admitted to being stunned by the warmth and fidelity of a ?Christmas Carol? featuring the famously nearsighted cartoon character voiced since 1949 by Cleveland native Jim Backus.
?Somebody probably said it couldn?t be done but somebody was wrong,? Daily Variety?s reviewer wrote.
Mr. Magoo?s Christmas Carol
What: A 50th anniversary airing of television?s first animated Christmas special. Also released in July as Blu-ray + DVD collector?s edition by Classic Media (christmasclassics.tv).
When: Saturday, Dec. 22, at 7 p.m.
Where: NBC.
Still, despite the glowing notices, ?Mr. Magoo?s Christmas Carol? quickly was eclipsed by the enduring popularity of the animated Christmas specials that followed it: ?Rudolph the Red-Nosed Reindeer,? ?A Charlie Brown Christmas,? ?How the Grinch Stole Christmas,? ?Frosty the Snowman.? Each of those holiday favorites has been getting an annual network re-airing since its premiere.
The last NBC airing of ?Mr. Magoo?s Christmas Carol? was in 1967.
?It slipped into syndication and obscurity,? Van Citters said during a telephone interview. ?It has been overlooked, underrated and underappreciated. No songs were ever released from it. There was no soundtrack. It has remained an overlooked gem for decades.?
Thanks to the 50th anniversary, however, some overdue recognition is on the way. Classic Media released a Blu-ray + DVD collector?s edition of ?Mr. Magoo?s Christmas Carol? in July, featuring a commemorative booklet by Van Citters. And Saturday, Dec. 22, at 7 p.m. there will be an airing NBC.
?It?s important for another generation to discover it, because it?s a really effective telling of the story,? Van Citters said. ?It really does deserve to be part of everybody?s Christmas memories.? ?
Reasons why ?it's worthy
It certainly does, for many reasons. First, it remains remarkably faithful to the language and the spirit of the Dickens story about Christmas spirits. Although cuts had to be made for an hour special, this adaptation uses many lines right out of the book.
Second, there is the music. Producer Lee Orgel aimed for the best Broadway had to offer. He first approached Richard Rodgers of Rodgers and Hammerstein (?South Pacific,? ?The Sound of Music?). Rodgers was intrigued and enthusiastic about composing original ?Christmas Carol? songs but too busy to tackle the assignment.
Orgel then approached Frank Loesser (?Guys and Dolls,? ?How to Succeed in Business Without Really Trying?). He also was interested. He also was too busy.
Composer Jule Styne and his new lyricist, Bob Merrill, had hit a snag in the troubled development of a new Broadway musical to be called ?Funny Girl.? They accepted the challenge.
Holed up at the Beverly Hills Hotel, Styne and Merrill wrote almost all of the special?s songs at the end of March and in early April of 1962. At one point, Orgel stopped by and heard Styne playing the piano and Merrill singing along. He thought the song was sensational and asked if it was a solo for Magoo?s Scrooge.
Styne and Merrill told him that it wasn?t for ?A Christmas Carol.? It was for ?Funny Girl.? It was ?People (Who Need People),? which would become a huge hit for Barbra Streisand.
Even without ?People,? the Styne-Merrill ?Christmas Carol? songs give this production a richness not found in most animated specials. They include three moving numbers (?Winter Was Warm,? ?Alone in the World? and ?The Lord?s Bright Blessing?) and the hilarious ?We?re Despicable.?
?A lot of people have tried animated versions of ?A Christmas Carol? over the last 50 years, and none of them is as good as this one,? Van Citters said. ?I think it really boils down to the songwriters. The Styne-Merrill songs really enhance the story.? ?
Worries prove ?shortsighted?
A third reason ?Mr. Magoo?s Christmas Carol? works so well is the clever concept ? a play within a play. The idea is that we?re watching a stage adaptation starring Quincy Magoo as Scrooge. The opening shows Magoo driving to the theater, singing the upbeat ?Back On Broadway.? This was the biggest gamble of all. Would viewers accept the myopic Magoo in a role requiring so much emotional range?
?Let me tell you something,? the Chicago Daily News critic raved, ?as it turned out, Magoo did an excellent job as Scrooge.? ?
A 12-year-old future critic was watching the premiere airing and echoed that assessment.
?I vividly remember seeing the show the night it first aired in 1962, which happened to be my 12th birthday,? said Hollywood historian Leonard Maltin, whose many books include ?Of Mice and Magic: A History of American Animated Cartoons.? ?It was probably the first time I?d seen a dramatization of the Dickens story, and I thought it was very effective. All these years later, having digested countless other interpretations, I still have a soft spot in my heart for this hourlong show. And Mr. Magoo was very well cast as Ebenezer Scrooge.?
A fourth reason that can?t be dismissed is the splendid work of Backus, who grew up in Bratenahl. Before ?Mr. Magoo?s Christmas Carol? aired, he had appeared with James Dean in ?Rebel Without a Cause? and with Humphrey Bogart in the newspaper drama ?Deadline ? U.S.A.? After the special, he was best known for playing millionaire Thurston Howell III on ?Gilligan?s Island.?
Yet the producers wondered if Backus was up to the singing required in ?A Christmas Carol.? Briefly, they considered using Robert Goulet for Scrooge?s singing voice.
?They had just used Goulet in the animated feature film ?Gay Purr-ee,? but thank goodness they stuck with Backus,? Van Citters said. ?Not only would it have been jarring to hear Goulet?s voice coming out of the Magoo Scrooge, Backus does some very touching work, particularly on ?Alone in the World.? ?
On a personal note, I was 6 years old when ?Mr. Magoo?s Christmas Carol? first aired, and it was my introduction to both Dickens and the magical notion of seeing stories brought to life by actors on a stage. Although a TV cartoon, it began a lifelong fascination with Dickens and the theater.
Given everything this special accomplished on so many levels, Mr. Magoo?s best-known catchphrase never seemed more apt: ?Oh, Magoo, you?ve done it again!?
To reach Mark Dawidziak of the Cleveland Plain Dealer, send an email to mdawidziak@plaind.com, or call 216.999.4249.
ScienceDaily (Dec. 5, 2012) ? Three University of Chicago chemistry professors hope that their separate research trajectories will converge to create a new way of assembling what they call "designer atoms" into materials with a broad array of potentially useful properties and functions.
These "designer atoms" would be nanocrystals -- crystalline arrays of atoms intended to be manipulated in ways that go beyond standard uses of atoms in the periodic table. Such arrays would be suited to address challenges in solar energy, quantum computing and functional materials.
The partners in the project are Prof. David Mazziotti, and Associate Professors Greg Engel and Dmitri Talapin. All three have made key advances that are critical for moving the project forward. Now, with $1 million in funding from the W. M. Keck Foundation, they can build on their separate advances in a concerted way toward a new goal.
"If you look at the history of science, a major development starts with people of different backgrounds talking to each other and learning from each other and doing something really revolutionary rather than incremental," Talapin said.
Developments in Talapin's laboratory form the core of the project. A synthetic inorganic chemist, he specializes in creating precisely engineered nanocrystals with well-defined characteristics.
Nanocrystals consist of hundreds or thousands of atoms. This is small enough that new quantum phenomena begin to emerge, but large enough to provide convenient "modules" for the design of new materials. "It's an interesting combination in that you build materials not from individual atoms, but from the units that resemble atoms in many ways but also behave as a metal, semiconductor or magnet. It's a bit crazy," Talapin said.
The potential of the new arrangements may exceed that of existing elements. Chemists cannot tune the properties of hydrogen or helium, for example, but they can tune the properties of nanocrystals.
"You build chemistry from atoms, and quantum mechanics provides principles for doing that," said Mazziotti, referring to the laws of physics that dominate the world at ultra-small scales. "In the same way, we envision tremendous opportunities in terms of taking nanocrystalline arrays and nanocrystals as the building blocks for new structures where we assemble them into strongly correlated systems."
Nanocrystalline building blocks
The essence of strong correlation, of chemical bonds, of chemistry generally, is the connections between particles and how properties of these particles change as they bind to one another, Engel noted. "It's about new emerging properties coming from strong mixing between the electronic states of particles, the same way two atoms come together to make a molecule," he said.
Hydrogen and oxygen gases have very different properties. Yet when two hydrogen atoms share electrons with an oxygen atom, they form water. The UChicago trio's ambition is to extend this framework from the level of individual atoms to the level of small, functional objects, such as metal or magnetic semiconductors.
The key to their project is controlling the degree of correlation between electrons on different nanocrystals. In 2009, Talapin and his collaborators developed a way to control the motions of electrons as they move from one nanocrystal to the next. Their "electronic glue" enables semiconductor nanocrystals to efficiently transfer their electric charges to one another, an important step in the synthesis of new materials.
"That glue is provided by a special tuning of the behavior of the electrons," Mazziotti said. "You want the electrons to have their motions correlated in a special way to allow the efficient transfer of that energy from one nanocrystal to the other." Achieving greater control of correlated electrons -- those whose motions are linked to each other -- on different nanocrystals is the key to success in the Keck project.
"If we can enhance that, then we can essentially develop a whole palette of new materials that essentially derives from using the nanocrystals as building blocks and strong correlation as a way of tuning, essentially, the degree to which or how they talk to each other," Mazziotti said. "We want really efficient transfer of energy and information between the different units. Previously in the area of nanocrystalline arrays, the nanocrystals only communicated with each other very weakly."
Developing a new palette
Mazziotti and Engel bring theoretical and spectroscopic advances, respectively, to the collaboration. Mazziotti's advance provides an alternative to traditional approaches to computing strongly correlated electrons in molecules, which scale exponentially with the number of electrons. He has solved a longstanding problem that enables calculations using just two of a molecule's electrons, which dramatically decreases the computational cost.
His studies of firefly bioluminescence and other phenomena have shown that as molecular systems grow larger, strong correlations between electrons grow more powerful and open new possibilities for emergent behavior. In the context of a semiconducting material such as silicon, emergent behavior is how individual nanoparticles effectively lose their identity, giving rise to collective properties in new materials.
"As the size of a molecular system increases, we see the emergence of new physics behavior and the importance of strong correlation of electrons," Mazziotti said. "The importance of strong correlation increases dramatically with system size."
The advance in Engel's research group was the development of a technique called GRadient-Assisted Photon Echo (GRAPE) spectroscopy, which borrows ideas from magnetic resonance imaging but is used for spectroscopy rather than medical imaging. Engel already has used GRAPE to observe the correlated motion and coupling between chromophores, which are light-absorbing molecules. Now he will apply the technique to nanocrystals.
"This, for the first time, will let us really see the direct nature of the electronic coupling that's at the heart of this idea of new bonding concepts in designer atoms," Engel said. "We'll be able to provide the experimental evidence that will combine the theory that David is developing with the new structures that Dmitri is building."
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The above story is reprinted from materials provided by University of Chicago. The original article was written by Steve Koppes.
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Last Friday I learned I?ll soon be writing a second book for a traditional publisher. I couldn?t feel more proud and excited. And I couldn?t feel more afraid and overwhelmed about being a multiple-book author.