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How to Save the Troubled Graphene Transistor

Unlike conventional semiconductors, graphene cannot be switched off, a problem that threatens to scupper its use in future generations of transistors. Now physicists think they’ve found a solution.

The writing is on the wall for the silicon chip. Transistors have been shrinking for the last half a century but they cannot get smaller forever. Most industry pundits think that the downscaling of silicon chip technology cannot extend much beyond 2026. The big question, of course, is what will replace it.

One possibility is graphene, which various teams around the world have used to make hugely fast transistors. Last year, one team clocked a graphene transistor at a cool 427 GHz. So you could be forgiven for thinking that graphene is the perfect silicon replacement.

Not so fast. There is a significant problem with graphene that makes it difficult to use in transistors– it has no band gap.

That means there is no energy range in graphene in which electron states cannot exist. Or in other words, it’s impossible to switch off graphene. And for a transistor, that spells serious trouble…

Click Here to Read the Full Article.

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Satellite Built by UAH Students ’99 Percent’ Ready for October Launch on NASA Rocket

The spacecraft conceived and built in Huntsville is virtually ready for launch and blast-off is less than three months away.

No, the Space Launch System is not suddenly on an accelerated program. Instead, it’s a group of students at the University of Alabama in Huntsville who have been working for more than three years on a tiny satellite that is scheduled to be sent into space in October.

Members of the Space Hardware Club at UAH were in San Luis Obispo, Calif., last week on the campus of California Polytechnic State University. The Cal Poly visit was to put the ChargerSat1 through readiness tests as a final hurdle toward the scheduled Oct. 30 launch.

The satellite got a “good thumbs-up,” according to team member Mark Becnel.

“We’re well past 99 percent (ready),” he said.

The project began in 2010 when the club applied for a spot on a future NASA launch…

Click Here to Read the Full Article.

Selecting the Correct Shoecover

Shoecovers: How to Choose the Best Product for Your Cleanroom

Shoecovers are used in most controlled environments, though few operators who wear them give much thought to these essential critical environment consumables. A cleanroom spends an estimated 20 percent of its supplies budget on its operators’ disposable garments, including shoecovers, and there are misconceptions about which shoecover style are best for the controlled environment industry. After reading this white paper, many controlled environments might discover that they are using a shoecover that is not only inappropriate for their environment, but is more expensive than a better suited product.

With an understanding of the purpose of shoecovers and an awareness of the types of shoecover materials available, it can be assured that a cleanroom is using the best, cleanest and most appropriate product for its specific need.

Shoecovers: Materials and Background

Shoecovers were first introduced in the medical industry as a way to control foot-borne contamination in surgical rooms and hospitals. This shoecover is a non-woven material with a primary substrate of spun-bond polypropylene (SBPP). It offers an elastic ankle cuff, which makes it easy to slip on over a regular shoe. When the operator leaves the clean area, he or she removes the cover and throws it away.

Because SBPP has a smooth texture, there is a challenge to keep its wearer from slipping on

slick floor surfaces. In a hospital setting, this problem was easily solved by adding a coating of paint along the bottom of the shoecover, called a “tread.” Shoecovers with this tread are referred to as “anti-skid.”

When the controlled environment industry looked to controlling foot-borne contamination in its cleanrooms, it borrowed from an industry with similar products. However, polypropylene (PP) presents several problems in a controlled environment setting.  PP is a non-woven material, which means that it can and will shed particles. It also tears easily, increasing the shed particles, and it will absorb any moisture on the floor, increasing the possibility of tearing and creating a slip hazard for an operator.

In other words, though PP shoecovers prevent contaminants from a shoe worn outside the controlled environment from getting out into the cleanroom, it creates a contamination and safety hazard all its own. Anti-skid PP shoecovers compound this same problem: the paint coating can also shed. One only needs to check a critical environment’s prefilter to its HEPA (High Efficiency Particle Airflow) system or evidence of this particulation.

Polypropylene Shoecover Alternatives

The challenges critical environments face when selecting a shoecover include reducing the chance of creating more contamination with a particle-releasing material like SBPP, as well as increasing the safety of the operators by using an anti-skid tread.

  • Cleanroom Shoes

Cleanroom shoes are an option for environments looking to cut down on the waste created with disposable cleanroom garments and on particles generated from SBPP substrate shoecovers. Cleanroom shoes are designed for comfort, as they are made specifically for operators whom are often on their feet all day. They can be made ESD compliant, and slip on for ease of gowning. They will have slip-resistant soles and can be easily washed and wiped.

The cons associated with cleanroom shoes are cost and storage. The shoes can be upwards of $40 a pair, and must be stored within the clean environment; removing them from the cleanroom would defeat their purpose. Many controlled environments lack the space and funds to accommodate cleanroom shoes.

  • Polyethylene-Coated Polypropylene Shoecovers

These shoecovers attempt to protect against PP’s moisture-wicking trait by coating the PP material with polyethylene, a plastic-based substrate. This creates a more durable shoecover, one that won’t tear as easily as PP alone. However, this shoecover is created by laminating the plastic on the outside of the PP.  Because the substrates have different tensile strengths, the material will tend to delaminate during extended wear.

 

  • Cross-Linked Polyethylene Shoecovers

Considered one of the most economical options, non-particulating, extruded cross-link, 100-percent polyethelyne cleanroom shoecovers offer a solution to many of the problems created with SBPP shoecovers.

Constructed of a plastic-based substrate, cross-linked polyethelyne (CPE) shoecovers are cleaner, and the embossed pattern gives the bottom friction and makes them inherently anti-skid without the need for a coating that will particulate.   They last longer, as they are less prone to tearing than SBPP.   Available in three standard thicknesses (3,5,8 mil) these shoecovers can often be worn all day.  The heavyweight 8 mil can be worn multiple days, provided that it is properly stored in the gowning room.

The cons of CPE shoecovers are that the ankle cuff is placed in the center of the shoecover – not toward the back as with alternatives – creating a need for the operator to be re-educated as to why the change merits the effort required.

 

  • Polyethylene-Coated Polypropylene Shoecover with a PVC Sole

A coated polypropylene cleanroom shoecover with a PVC sole is considered the cleanest and most durable option in a disposable shoecover. It is also the most expensive option.

The PVC sole is durable, and its sticky texture makes it anti-skid, even on wet floors. The interior of the shoecover is comfortable polypropylene, the outside is coated with polyehtelyne to reduce particulation. These shoecovers are autoclavable and can be worn for up to a week.

Conclusion

There are several factors to consider when finding the appropriate cleanroom shoecover for an environment’s needs: comfort, safety, cost and cleanliness. Each controlled environment must assess all of these when making a decision about the shoecover best suited for its needs.

Download a copy of “Shoecovers: How to Choose the Best Product for Your Cleanroom

Defining Cleanroom Gloves, Know the Difference

Do you know the difference between Cleanroom grade gloves and standard disposable glove?  Well there is a lot that comes into play when defining and selecting the proper glove for the process and environment at hand.  We have put together a Cleanroom Glove guide that gives a rundown on everything from the substrate and manufacturing process all the way to sizing. disposable

Click this link to view the Valutek guide to cleanroom gloves

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Marla Bouise Promoted to Senior Account Manager

Valutek is proud to announce that Marla Bouise has been promoted to Senior Account Manager.  Marla has been with Valutek for over 1-year and specializes in saving clients time and money by bundling consumable products together to provide the best overall value.  Marla is an 18-year glove-industry veteran that understands the importance of finding her clients the right glove at the right price.

Don’t forget, we are offering FREE shipping to all credit card orders over $100.  Just enter the coupon code “2012” during checkout!  And our WarehouseWipeout sale is still in effect, click here to view the list that can save you 30% on certain products.

2012 Product Price Listing

Happy New Year from Valutek!

Valutek has officially announced our 2012 price listing.  Our new price listing can be viewed  at Valutek.com on the home page, or by clicking here.  While creating the price list, we worked to isolate our top selling products from our special order products that we usually have a very limited quantity of.

We made room in our warehouse for the high demand products, and in the process we created a list of excess inventory items that can be found on the Valutek.com promotions page, or by clicking here.  The Warehouse Wipeout list of excess and special order product is being offered for 30% off the retail price!  But this is only being offered for a limited time, so contact Valutek today!

We are also happy to celebrate the New Year and offer any credit card order placed over $100 FREE FedEx Ground shipping from now until January 31st, 2012.   All you have to do is enter the promotional code2012” at the end of checkout!

Exploring Engineering and the Sanford Underground Laboratory

There are two very interesting articles about two groups entering cleanrooms that most likely have not in the past.  One is a group of students exploring the thought of pursuing education in engineering and the second is a group of reporters that were allowed to take a tour of an underground laboratory in South Dakota.

A unique summer program in Louisville is inspiring and providing information to teens about engineering’s wide range of fields and were it is applied.  The Brown-Forman INSPIRE program, or Increasing Student Preparedness and Interest in the Requisites for Engineering program, has been offered since 1981.  The program is specifically designed to increase awareness of the diversity of engineering fields for high school students and prepare them for engineering programs in college.  The program allows the students to suit up and enter a cleanroom where nanotechnology and microelectronics are currently being developed.  To read the article and view images of the INSPIRE program, Click here.

 
The second article brings a more complex and scientific look into a cleanroom environment.  Media was allowed to join a tour of the Sanford underground laboratory, a former gold mine 4,850 feet underground that has been rebuilt to conduct “dark matter” experiments.  Throughout the tour media was able to view many interesting scientific processes at work.  They observed a cleanroom where workers wore full body coveralls as they processed copper through acid baths during a purification process, engineers laser scanning the newly constructed cavern where a new lab addition will be built, and a 40 foot high cavern where a 100ton tank of water will be built to conduct a future dark matter experiment.  To read the full article click here or for more information on the Sanford underground Lab click here.

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