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Monday, July 25, 2011

Marbles


The History of Marbles



It’s hard to pinpoint the exact moment in history when the first toy marble was made, or even if it was made explicitly for the purpose of play, since marbles predate recorded history. Ancient marbles have been regularly found in Egyptian tombs, Greek and Roman archaeological digs, and even before that, since marbles have also been found that date back to the Ice Age.

It has been theorized that the first marbles, used for play, were just small pebbles or balls made from natural clay. The succeeding materials used for marbles were china, real marble, and glass. They were all handmade until the year 1848 brought the invention of the marble scissor by a German glass blower, which made production much easier.

Large-scale machine production of toy marbles began a few decades later, when machine-made marbles were first rolled out in Germany and the United States in 1890, and the marble craze happened afterwards.

In the 1950s, the use of marbles really exploded. Also, the cat’s eye marble was created by injecting colored glass in a regular marble. Various effects were achieved with the use of different colored glass and different shapes or swirls.

These days, marbles have become such an important part of culture that they are not merely toys but also miniature art pieces, with some rare and expensive ones fetching over $5,000 a piece. The most expensive set on record was a box of twelve marbles made in 1930, with each marble stamped with a different cartoon character such as Krazy Kat and Orphan Annie. This cartoon marble set was originally sold for the price of 25 cents, but the same box today would cost you at least $900.

Regardless of where they began, marbles are a simple yet fascinating toy that brings out the child or collector in many of us.



Marble Collecting




Collecting marbles has become one of the fastest growing hobbies in recent years. Interest in the collectible side of marbles has spread to all ages and many parts of the world. What used to be the simplest of playthings are now sometimes highly sought-after works of art that fetch incredible sums.The collecting of marbles is more than just a matter of dealing with the value of old marbles. It is also about the nostalgia that these toys invoke in the collectors and the people they share their passion with. Every weekend of the year, there is a marble show going on somewhere, and collectors often hunt for treasures at auctions, flea markets and antique shows.

The art of finding collector marbles is relatively new. It is only in the last twenty years or so that it has turned from a game into a collectible. In the beginning there were just a handful of collectors; now there are literally thousands.

Generally speaking, collectors marbles fall into three main categories: machine made, hand made and contemporary. Hand made marbles are obviously those made by an individual craftsman. While these marbles have existed for hundreds of years, they were originally made of clay or stone and aren't very collectible today. The hand made marbles that are of interest to serious collectors are the glass marbles that were created in Germany in the last half of the 19th and first part of the 20th century. Without a doubt, hand made marbles are impressive for both their technical and artistic features. Each one of them contains the unique skill and art of the craftsman who made them. Working with glass is a challenge under any circumstances; to create something with the beautiful colors, design and balance of the best hand made marbles is another thing altogether.

Although the hand made marbles have traditionally been the most collectible, in recent years machine made marbles have gained some popularity among collectors. In the mid-1980s, there was a sharp increase in the number of people getting involved with marble collecting, and prices for many hand made marbles increased dramatically. Collectors sought out other kinds of marbles to buy and realized that they could purchase a number of impressive-looking machine made marbles for the price of one hand made. For much of the 20th century, machine made marbles were almost exclusively made in the United States, while the hand made marbles were usually a product of Germany. The market for machine marbles has been much less stable than that of the hand made.

The value of marbles is determined by several factors. Here are four of the most significant ones. 
  
The most important factor is rarity of type, It’s important to realize, though, that just because something is rare that doesn’t mean that it is in demand and therefore valuable. Something can be so rare that it is basically unknown and not at the top of anyone’s list of collectible marbles. 
  
Condition is the second factor. Grading the condition is not an exact science and is subject to the opinions of the collector. There have been some attempts to set up a standard way of describing condition, such as the Marble Collector’s Society of America's grading system of "Mint," "Near Mint," "Good," and "Collectible." Other classification systems have also been used. Whatever criteria is used, there is no doubt that any kind of damage or wear to the outer surface of a marble will reduce its value. This is true of both hand made and machine made marbles, but more so for machine made. 
  
The size of a marble is the third factor that affects value. All marbles are measured by their diameter in inches. Machine made marbles are usually between 1/2" and 3/4" because regulations at most marble tournaments set the size of shooter and target marbles within that range. Hand made marbles usually do not exceed 1-1/2" because the weight of the glass would not allow the creation of any size bigger than that. It is difficult to make a general statement about the collectibility of one size versus another because rarity of size changes from one type of marble to another. 
  
The fourth factor is simply the visual appeal of the marble. This is determined by the strength of the colors and the balanced symmetry of the design. Speaking in generalities, the brighter and more balanced the design, the more valuable the marble. This factor is even more subjective than condition, so it is hard to fit it neatly into any classification system.



Types of Marbles


Marbles come in an astonishing variety and are commonly classified according to their size, appearance, and materials they are made from. Glass marbles are probably the most popular today, but they can also be made from clay, crockery, china, real marble, stone ivory, agate, steel and other materials. 

Generally, marbles are around 1/2-inch across, but they can range from less than 1/4-inch to more than 3 inches. Marble players often use terms like jumbo, pee wee, queenie, bumbo, bumboozer, and boulders to describe marble sizes. 

Sometimes the names given to marbles describe the materials from which they are made and sometimes they describe their appearance. Here are some of the major classifications. 





Alley or Real describes a marble that is made from real marble or alabaster. Alley stands for alabaster. These usually have wavy patterns with lots of color. Common names for these marbles include onyxbumblebeecorkscrew, and swirl. Other examples include: 

Oxblood—these have streaks that resemble blood.

Onionskin—which contain a pattern that looks like an onion.

Lutz—the name comes from a skating term, describing a pattern that resembles this marble's streak.

Toothpaste—distinct waves of black, orange, white, blue and red.

Cats Eye—these are created by injecting colored cores into the marble, which look like eyes in the center of the marble.

Croton Alley or Jasper should not be confused with the alley marbles listed above. Instead, they are made of either glazed or unglazed china that is marbled with blue. These are usually larger than the other alley marbles. 

Commie or common marbles are usually brightly painted but are made of clay and don't often retain their finish over time. They generally don't have much value. 




Steely is just what it sounds like, made of steel. 

Sulphide marbles are clear and have objects embedded inside of them. 

China and Plaster marbles are both made from china. China marbles are those that have been glazed, while plasters are those that have not been. Both of them have lines of various colors that sometimes cross each other, forming plaid designs. They also form circles called bull's eyes. Like any other form of china, they are created in wooden molds, then baked, and painted. 

An Aggie is made from agate, or sometimes carnelian and are usually quite beautiful. They vary in color from gray to blood red and sometimes have stripes or mottlings of different colors. When they are created, the rock is broken down into smaller pieces and then a hammer is used to form them into crude balls. They are then worn down on a grindstone until they are perfect spheres. They are then polished polished by hand. Aggies are perfect when you are making a difficult shot because of their balanced weight and symmetry. 

Crystal or Clearie marbles are made of clear colored glass, and are often known asrubiesbloodsglimmers, or opals. They too are often beautiful but don't stand up to wear and tear. After they have been used, their finish becomes full of nicks and has a dull sheen. Sometimes these marbles are called agates, so the genuine agate is often referred to as "real" to distinguish it from the glass ones.



The terms galaxy, cloudy, swirly, mica, and milky are also familiar to many marble players.

Take a look at the categories on the right and peruse the selection of marbles available for purchase on eBay. Be careful, though, you might get hooked on collecting these beautiful toys or showpieces!



Uses Of Marble

Just as in ancient Greek and Roman society, marble represents beauty, elegance, sophistication in our modern era. It has become an increasingly popular choice for countertops, flooring, fireplaces, foyers, bars, tables, showers, and windows. It graceful style, ability to reflect light, and ease of cleaning (see how to clean marble) have made it the stone of choice amongst the elite. 






Best Cleaner for Marble Shower Mold

Marble showers may scratch and stain over time and will lose their shine. It is essential to use a specially formulated cleaner on the marble tiles which will not leave any harmful residues, and will not leave the surface slippery. The best cleaner for Marble Shower Mold is a specialist cleaner such as Stone Soap Ultra. Avoid abrasive or acid-based cleaners which will damage and etch the marble permanently.






How to Install Marble Tiles




Installing marble tiles is much the same process as installing ceramic tiles, but marble tiles do have square edges and natural variations, whereas ceramic tiles are beveled and consistent in shape. A solid surface must be prepared before installing marble tiles, then the tiles must be inspected for cracks. The marble floor tiles are secured using a thinset adhesive and must be laid evenly to avoid lippage.



How to Polish Marble

The best way to polish marble is to wipe the marble tiles or marble slab with a damp rag and buff dry to a shine with a chamois leather cloth. A specialist marble cleaner may be used for tough stains, and coasters or mats should be used to protect marble surfaces from damage. Marble flooring should be treated with a stone sealer and can then be polished with a standard non-abrasive solution.


marble bathtub

How Marbles are Made.

Stone marbles were manufactured in immense quantities fit Saxony for exportation to the United States, India, and China. The common marble is manufactured of hard stone quarried near Coburg, Saxony, and the process is practically the same as that used by nature in grinding out the little round pebbles originally used by the children of long ago.
Nature, though constantly busy, is slow. We do not want to wait a thousand or maybe a million years for her to get our marbles ready. Our fingers might be too old to shoot with them, so we adopt nature's principles, but make more haste. In place of frost man uses a hammer to break the stone into fragments.
The hammer breaks the bard stone into small squares, or, more properly, cubical shaped blocks. These are placed a large millstone one hundred or two hundred at a time. The millstone has several grooves cut in it in the form of rings, one ring inside another, or, as your Geometry would put it, in the form of concentric circles. Over this a block of oak of the same size as the lower stone rests on the small square fragments and is kept turning while water flows upon the bottom stone.
Power is supplied by a water-wheel, and when the machinery is set in motion the little cubes are compelled, by the pressure and motion of the upper piece, to roll over and over in their circular tracks, and round and round and round they travel like circus hones in a ring. In fifteen minutes' time the mill does what nature takes years to accomplish, and the little blocks of stone are turned into small stone balls. These are the unfinished marbles and need something.
One such mill can turn out two thousand marbles a week, and if there are four or five sets of millstones running, eight thousand or ten thousand a week can be manufactured. In another part of the establishment the waterwheel turns a number of wooden barrel-shaped receptacles, something like the copper ones used for making candy in this country. Inside the wooden casks are hard stone cylinders. These revolving cylinders smooth the marbles, which are compelled by the motion of the machinery to keep up a constant rubbing against each other and against the stone cylinder. When they are smooth enough the dust made by the last process is emptied from the casks and fine emery powder substituted. This gives finish and polish to the marble.


antique marbles
One of the most aesthetic uses of the marble has been the statues. There are different types of marbles that have been used to curve amazing shapes out of them. However, some of them have been preferred by the artists, while some others are not.
The Parian marble is also very famous among the architects and sculptors of the Greek civilization. It could be found in the Mount Marpessa and other places in the isle of Paros. The ancient writers called it lychnites that refers to a lamp. This is because the quarries were worked by the lamps. Among the various noticeable work on it, the Venus de Medici is certainly the most well known.
However, if one considers the popularity of the Greek marbles, the Carrara marble will be right there on the top of the list. In fact, this is the stone that is used by the best sculptors of this present time. The stone can be found in huge amount in the region of the Apuan Alps as well as in Massa, Carrara and Serravezza. During the regime of the Augustus, the Romans used to take marble from this area and used them in architecture. However, the finer varieties, that became so popular among the artists, were discovered later.
Legendary artists like Canova or Michelangelo used this stone to execute some of their masterpieces. The snow-white color of the purest version of this stone has also been used to create other beautiful sculptures as well. The common variety of this marble has a blue shade and is not suitable for statues. However, the geologists are not quite sure about the age of the stone.
Giallo antico, also known as numidic yellow is a unique marble that was derived from North Africa. It seemed that the Romans imported the stones through ships. In fact, the trend of shipping in marble from different corners of the world was quite a popular one in the Roman Empire.
The Lumachella marble was derived from Carinthia and it has a mixture of black, grey and white spots. This is a very rare type of fossil marble that contains the small snails. The Cipollino has a unique texture of white and pale green. It is assumed that this Greek marble was the first colored marble that was taken to the Rome.





Rare Types of Marbles


Latticinio Swirl

Rare marbles of value to collectors tend to fall into two distinct categories best described as modern and primitive. Modern marbles which are of value to collectors are often hand crafted by artists and can exceed five inches in diameter. Primitive marbles, on the other hand, are those marbles manufactured either by hand or by machine previous to the 1960s. Among the most valuable marbles are those which were manufactured in Akron, Ohio, or which were hand-crafted in Europe in the late 1800s.
Rare Types of Marblesthumbnail
Vintage marbles come in every color and design
    • Latticinio swirl marbles date to the 1900s and were produced in Italy, although some originated in Germany. The indicative trait of Latticinio Swirl marbles is the swirl pattern encapsulated within the glass. In all cases, swirls of brilliant color twist from one hemisphere to the opposite hemisphere. These marbles can be quite valuable to collectors, even in less than perfect condition due to their beauty and the fact that they were handmade in early years. Some handmade Latticinio Swirl marbles are still being hand-crafted by artists.

    Ceramic Marbles

    • Ceramic or China marbles are among the oldest marble types known to exist. By the 1870s, ceramic marbles were being mass produced and are hence are less desirable than glass marbles. They are also considered less attractive than their glass counterparts. Extremely old or hand-glazed marbles are still sought by collectors, however. These marbles will often look handmade, with less than perfect shapes and brush stroke marks in the glazing.
      Painted Ceramic Sink

    Agate Marbles

    • An agate marbles is a piece of quartz which is ground down and polished smooth. Much denser than typical glass marbles, agate marbles were popular with children because it was easy to knock glass marbles out of the circle with an agate marble. They can be identified by the alternating dark brown, crimson or even blue bands of color set against a light colored white, yellow or eggshell colored background. Akro Agate Marbles in Akron, Ohio, was the largest producer of Agate marbles until the 1920s.

    Modern Art Marbles

    • Collectors frequently collect more than just rare vintage marbles. Modern art marbles can make up a very expensive portion of a collection. Among the more popular styles are marbles which encapsulate small objects such as spaceships or even much smaller marbles which are called "planets." These art marbles often exhibit explosive use of color within the marble. Because they are handmade, no two modern art marbles are exactly alike, making them rare and sought after items.


      Handmade Vintage Swirl Marbles
       Swirl marbles maybe the most distinct type of marbles. These are traditionally glass marbles that are swirled with different colors. These marbles come in varying color combinations and are really quite beautiful.
       Germany has produced some classic swirl marbles. You can find gorgeous blue, red and white swirled marbles. Germany made some of the best swirl marbles. These items are perfect for any vintage marble collector.
       Some of these marbles can be dated back to the 1800’s. But don’t worry swirl marbles are not hard to find. You can find pretty vintage swirl marbles for sale on EBay.







 Picture the beautifulness of Peacock feathers. Now picture those feathers swirled in the center of a handmade glass marble? These classic marbles are really pretty. The way the colors swirl make this marble one of the most gorgeous and unique marbles. The marbles can have varying colors inside them, making each one truly unique.
Handmade Vintage Peacock Swirl Marbles

 While the colors tend to not be as bright as other swirl marbles, they color combinations are still wonderful. The colors aren’t as bright because makers want to stay true to the peacock colors. Many designers have made peacock swirl marbles. You can find an array of pretty peacock swirl marbles on eBay. These marbles will go beautifully with the other swirl marbles.



Handmade Vintage German Triple Ribbon Marbles
 Just like the name suggests this classic German marble has three distinct ribbons wrapping around the and through the center. These German marbles are handmade and you can tell because of the detailed design.
 The ribbons themselves can come in different colors. The color combinations of the ribbons are really beautiful and are what give each marble an individual style. You can find this type of vintage German Triple Ribbon marble on eBay. These collectible German marbles are perfect for the avid marble collector.







Handmade Vintage Shooter Marbles
 Shooter marbles are made for ….well shooting. There are varying games of marbles. One would use the shooter marble to shoot other marbles in the game. These marbles have no set design. They can come in many different versions. They can tend to be larger than traditional marbles.
 You can find shooter marbles with swirls, specks or in solid colors. Also you can find these marbles from as far back as the 1800’s. of course there are more contemporary versions of these but antique Shooter marbles are a must have for a collector. You are sure to find the color and design you want right on eBay. eBay offers a wide variety of shooter marbles to buy. Find them now!



Handmade Vintage Akro Corkscrew Marbles
 Corkscrew marbles are bright and colorful! There are characterized by the swirl of color amid a cream or white marble. They are not ribbon marbles like the German designs. It is one swish of color. The line of color does not go in any straight line but in a corkscrew shape.
 They come in many different colors and no to marbles are going to come out the same. Each marble will be a unique design. They are sets and collections of these marbles on sale at EBay. The more vintage the marble is the more they will go for. It’s a small price to pay for beautiful classic marbles such as these.




Handmade Vintage Sulphide Marbles
 There is nothing like a Sulphide marbles. These are clear colored marbles with items set in the middle. Antique sulphide marbles would be a unique addition to your marble collection. Sulphide marbles have an array of items set in them. They have been also around since the 1800’s. A popular figure to have in vintage marbles is crosses and other religious emblems.
 Animals are also a popular sulphide marbles. You can find one with birds, dogs and other animals. EBay has an array of these one of a kind Sulphide Marbles for you to collect. Some Sulphide marbles are rarer than others. Look for the oldest marbles, so you know you are getting a great antique.



Handmade Vintage German Double Ribbon Marbles
 These marble were mostly made in the 1800’s. The German vintage marbles traditionally have the double swirl in the center as its core. This design is similar to the Latticino swirl. The core can come in varying ribbon colors. Often the German double swirl ribbon marble has different color bands circling around the marble.
 You can find different designs and colors on EBay. If you collect classic marbles then you have to have this type of marble! All these marbles are available at affordable prices.





Handmade Vintage German Blue Tint Marbles
 German blue tint marbles are marbles that have a distinct design with a slight blue tint to the overall marble. Like stated before Germany made some of the most recognizable marbles in the day. These are no exception. They can have a beautiful swirl like in the ribbon swirl marbles and Latticino or a different design all together.
 Find the perfect vintage German blue tint marble on EBay. You can add this marble to your collection of classic marbles.





Shrimp Etouffe



Active Time:  15 Minutes
Total Time:  30 Minutes
Yield:  Serves 4
The Acadian classic - shrimp smothered in a roux-thickened sauce of vegetables and spices - is every bit as luscious as the original. For extra heat, add more cayenne or a touch of Tabasco sauce.
RECIPE INGREDIENTS
2 tablespoons cooking oil
2 tablespoons flour
1 1/2 cups canned low-sodium chicken broth or homemade stock
1 green bell pepper, chopped
2 ribs celery, chopped
onions, chopped
bay leaf
2 teaspoons salt
1/4 teaspoon cayenne pepper
1/2 teaspoon fresh-ground black pepper
1/2 teaspoon dried thyme
1 1/2 pounds medium shrimp, shelled
scallions including green tops, chopped
Boiled or steamed rice, for serving

DIRECTIONS
In a large frying pan or Dutch oven, heat the oil over moderate heat until almost smoking. Add the flour and whisk until it's the color of peanut butter, about 3 minutes. Whisk in the broth and continue whisking until the sauce starts to thicken, about 2 minutes.

Stir in the bell pepper, celery, onions, bay leaf, salt, cayenne, black pepper, and thyme. Bring to a simmer, cover, and cook over low heat until the vegetables are tender, about 15 minutes.

Add the shrimp and scallions and simmer until the shrimp are just done, about 3 minutes. Serve the étouffée over the rice.

Friday, July 22, 2011

2011 Movie Trailers : DAM999 3D | from Official Movie Trailers 2011

Immortals Movie Trailer Official 2011

Thor - Official Movie Trailer 2011 HD

Super 8 | Official Movie Trailer | 2011 HD

Battle Los Angeles - Official Movie Trailer #1 (2011) US | HD

Sanctum Movie Trailer Official (HD)

Thor - Trailer (OFFICIAL)

The Dark Knight Rises Full Teaser Trailer 2011 Official Cinema Movie Hol...

A Better Personal Health Record?



In the wake of Google Health's collapse, one company hopes to promote personal health tracking through employers.
  • BY COURTNEY HUMPHRIES



When Google recently announced it would discontinue Google Health at the end of this year, it left the fate of personal health records (PHRs) hanging. Unlike medical records kept by healthcare providers, Google Health offered a single place where people could store, analyze, and share their personal health information. However it needed to be improved by a fragmented health system that made it challenging to collect medical information, and it relied on the initiative of consumers to gather their own data.
Only some people are discouraged by Google Health's demise. Cambridge, Massachusetts-based Dossia, a PHR provider that began as a nonprofit consortium of large employers, recently announced the launch of Dossia Health Manager, which will expand the company's current PHR platform with new features.
Unlike Google Health and similar services, Dossia's system is linked to employer-sponsored health plans—its largest user is currently Walmart. Employers are interested in personal health records as a way to encourage healthy behavior—and thus cut down on the money they spend on insurance premiums. Dossia's system can track subscribers' health status and tie that information to incentives or rewards. For instance, it could determine whether people with high blood pressure are measuring and controlling their blood pressure and refilling their prescriptions. Dossia keeps employees' private information secure from employers by using security technology similar to the kind used by the financial industry.
Dossia CEO Michael Critelli thinks Google Health's fatal error was to require consumers to input their own information or request it from a doctor's office. "Consumers are not going to go to the trouble of assembling their health information," he says. Dossia's PHR system uses the leverage of large employers to request insurance, pharmacy, dental, and physician records from multiple sources. Critelli says Dossia is subject to more regulation than Google Health because it accesses health information directly. But he says it's worth it to take the burden off the consumer.
"The goal of Dossia is to merge clinical and nonclinical records," says Critelli. It can hold records of lab test results and prescriptions from a doctor's office, insurance information, and personal data from pedometers or health-monitoring devices. The expanded platform also provides a price comparison tool for people shopping for health services. It adds an option for a caregiver to take charge of the information of a family member.
But assembling information quickly and efficiently is no easy task. Critelli admits it's Dossia's greatest challenge. Legislation has given patients the right to control their own health information, but it doesn't require that health plans, clinics, and hospitals provide that information quickly and automatically at a patient's request, and many are reluctant to do so.
John Halamka, chief information officer of Harvard Medical School and Beth Israel Deaconess Medical Center in Boston, says that while it's important to aggregate information, it's even more critical to have information that's integrated with a doctor's office. So far, electronic health records have seen the most growth in "tethered" systems, which are connected to the clinician's office. "My sense is that tethered PHRs are growing much faster than untethered PHRs because patients find value in clinical office integration more than consolidation of their records in one place," he says.
Dossia's system offers consumers some of the advantages of untethered records—they are portable from doctor to doctor, and include data from different sources—as well as the benefits of tethered records, because the data is gathered directly from physicians.  

Pure Nanotubes by the Kilo

Amped up: This jumble of carbon nanotubes has tripled in volume after two runs through a growth process called amplification.
Credit: ACS/Nano Letters

ENERGY


An improved production process could make electrical transmission lines far more efficient.
  • BY KATHERINE BOURZAC

An improved process for making large amounts of pure metallic carbon nanotubes could hold the key to overhauling the electrical power grid with more efficient transmission lines.
Researchers at Rice University plan to generate a large quantity of this material by the end of summer. They'll use these nanotubes to make long and highly conductive fibers that could be woven into more efficient electrical transmission lines.
There are a few different classes of carbon nanotube, each with slightly different properties and different potential uses. Unfortunately, existing production methods result in a mixture of different nanotubes, with varying dimensions and wildly different electrical properties. Purely semiconducting nanotubes, useful for future integrated circuits, are in the mix with metallic nanotubes that could be used to make highly conductive wires. So nanotubes have to be separated by type, a slow and expensive process, says Andrew Barron, professor of chemistry and materials science at Rice.
"There is a subset of nanotubes that are the best conducting materials to be found, that don't lose any energy to heat," says Barron.

Barron is part of a group at Rice that wants to make something very large from these nanotubes: miles and miles of highly conductive electrical transmission lines for a more efficient energy grid, which will be important as the use of renewable energy grows. This was one vision of the late Rice professor Richard Smalley, who won the Nobel Prize in Chemistry for his codiscovery of fullerenes, a new type of carbon structure. The Rice researchers have made long, pure carbon nanotube fibers, but since they have been working from impure samples, these fibers are not as conductive as they could be.
Barron and his colleagues have now improved on a method for making pure nanotubes that they first developed in 2006. Called "amplification," it should eventually allow them to turn a nanogram of pure carbon nanotubes into a gram, then a kilogram, then a ton. They start by separating a small amount of pure metallic nanotubes from a mixture, and then attach a catalyst to the tip of each tube. They then put the nanotubes into a pressurized, temperature-controlled chamber and feed in a mixture of gases. Under these conditions, the nanotubes double in size, growing from the catalyst at the tip. The existing nanotube acts as a template that dictates the diameter, structure, and properties of the extra length of the nanotube. The nanotubes are then cut and the process is repeated.
Barron and colleagues first demonstrated amplification a few years ago, but it wasn't very efficient. In a paper published online in June in the journal Nano Letters, they described a combination of the right catalysts and growth conditions that would ensure that every single nanotube would be amplified. Previously they'd assumed these conditions should be identical to the ones used to make the starting batch of nanotubes, but it didn't work very well. Barron says they have now found the conditions to make amplification work.
The Rice researchers are using the amplification process to accumulate enough pure metallic nanotubes to make a fiber of the type that would be used to make an electrical transmission line. They've made long, conductive nanotube fibers in the past using a spinning process also developed at Rice, but they've had to use impure nanotubes to make any great length of the material.
Aaron Franklin, a researcher at IBM's Watson Research Center, says the new study probably doesn't "reveal the golden ticket for achieving high volumes of metallic-only tubes." The amplification process is still not producing very large quantities of the material, Franklin notes.
While the Rice group continues to work on amplification, other researchers are exploring alternative ways of making pure nanotubes in quantity. Mark Hersam, a professor of chemistry at Northwestern University, developed what is now one of the most commonly used separation methods. He founded a company called NanoIntegris to sell pure nanotubes. He says ramping up production "is now essentially an industrial optimization exercise."