Keeping electronics cool: Findings on modified form of graphene could have impacts in managing heat dissipation

ScienceDaily (Jan. 9, 2012) — A University of California, Riverside engineering professor and a team of researchers have made a breakthrough discovery with graphene, a material that could play a major role in keeping laptops and other electronic devices from overheating.

Alexander Balandin, a professor of electrical engineering at the UC Riverside Bourns College of Engineering, and researchers from The University of Texas at Austin, The University of Texas at Dallas and Xiamen University in China, have shown that the thermal properties of isotopically engineered graphene are far superior to those of graphene in its natural state.

The research efforts were led by the Professor Rodney S. Ruoff of UT Austin and Balandin, a corresponding author for the paper, "Thermal conductivity of isotopically modified graphene." It was published online Jan. 8 by the journal Nature Materials and will later appear in the print publication.

The results bring graphene -- a single-atom thick carbon crystal with unique properties, including superior electrical and heat conductivity, mechanical strength and unique optical absorption -- one step closer to being used as a thermal conductor for managing heat dissipation in everything from electronics to photovoltaic solar cells to radars.

"The important finding is the possibility of a strong enhancement of thermal conduction properties of isotopically pure graphene without substantial alteration of electrical, optical and other physical properties," Balandin said. "Isotopically pure graphene can become an excellent choice for many practical applications provided that the cost of the material is kept under control."

He added: "The experimental data on heat conduction in isotopically engineered graphene is also crucially important for developing an accurate theory of thermal conductivity in graphene and other two-dimensional crystals."

The research used the optothermal Raman method, a thermal conductivity measuring technique developed by Balandin. In 2008, Balandin and his group members demonstrated experimentally that graphene is an excellent heat conductor. They also developed the first detailed theory of heat conduction in graphene and related two-dimensional crystals.

The work presented in the Nature Materials paper shows that the thermal conductivity of isotopically engineered graphene is strongly enhanced compared to graphene in its natural state.

Naturally occurring carbon materials, including graphene, are made up of two stable isotopes: about 99 percent of 12C (referred to as "carbon 12") and 1 percent of 13C (referred to as "carbon 13"). The difference between isotopes is in the atomic mass of the carbon atoms. The removal of just about 1 percent of carbon 13, also called isotopic purification, modifies the dynamic properties of crystal lattices and affects their thermal conductivity.

The importance of the present research is explained by practical needs for materials with high thermal conductivity. Heat removal has become a crucial issue for continuing progress in the electronics industry, owing to increased levels of dissipated power as the devices become smaller and smaller. The search for materials that conduct heat well has become essential for the design of the next generation of integrated circuits and three-dimensional electronics.

Balandin, who is also founding chair of the materials science and engineering (MS&E) program at UC Riverside, believes graphene will gradually be incorporated into different devices.

Initially, it will likely be used in some niche applications such as thermal interface materials for chip packaging or transparent electrodes in photovoltaic solar cells or flexible displays, he said.

In a few years, it could be used with silicon in computer chips, for example as interconnect wiring or heat spreaders. It also has the potential to benefit other electronic applications, including analog high-frequency transistors, which are used in wireless communications, radar, security systems and imaging.

Balandin and the following researchers contributed to the findings in the Nature Materials paper:

The team at UT Austin, which performed the isotopic purification of graphene, included Ruoff, Shanshan Chen, a post-doctoral fellow, Weiwei Cai a former post-doctoral researcher who is now a professor at the Xiamen University and Columbia Mishra, a graduate student.

The team at UT Dallas, who performed molecular dynamics simulations that compared well with the stronger thermal connectivity of the isotopically engineered graphene, included Kyeongjae Cho, a professor, and Hengji Zhang, graduate student.

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Beginner's Guide To Managing Android Phone Movie Collection

You've just seen a preview of one of those breathtaking Hollywood movies and you're wondering how to place your movie assortment on your brand-new tablet or android phone for some on-the-move video greatness? Here are a few guidelines on how you can rip your Blu-ray and DVDs movies, transfer them in HandBrake, as well as sync your iTunes buys.

Sitting down on your lovely couch at home to watch a movie on your television set or a home theater computer is quite an easy process. You just need to insert the disc or click to open the file, and your movie is ready to be viewed. However, if you're a new android phone or tablet owner, having your Hollywood movie collection with you can be a very difficult process. In any case you lack an optical drive on your new tablet, and often most smartphones don't play sufficiently with video files maybe you apply an appropriate file format and superior resolution. Below, we've prepared a collection to take you through some of the difficult steps involved in having your movies in portable devices from your DVDs.

To begin with, you'll need to know how to rip your Blu-ray and DVD movies to your computer using MakeMKV and HandBrake respectively; therefore, no need to take your optical drives with you. The two applications which are luckily free will have your movies appear every bit as excellent on your computer as they are on the huge screen display.

Subsequently, you'll need to know how to utilize HandBrake to change movie files (from either downloads or maybe you own rips) into a resolution and format that your android phone or tablet PC can play.

Lastly, if you've perhaps previously been alternating around from one computer to another, you could have difficulties syncing iTunes Library buys. Well, if that's the case, then, you'll most likely need to allow your new computer to access your iTunes account and then unauthorized your old PC before you can actually begin syncing all your iTunes items.

Evidently, advanced computer users who are already familiar with nitty-gritty of every device they own be it a tablet PC or a smartphone they won't find these guidelines necessary, but for your family and friends who happen to picking up tablets or android phones lately, then they should consider filing this package for future reference to help guide them through every process step-by-step.

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Managing Defective Refurbished Phones

Buying refurbished phones are becoming more and more popular with people who have different tastes in owning cell phones. There are those that prefer to buy brand new cell phone units and there are those that like to buy used cell phones. The other sides of customers are those that buy refurbished phones.

Refurbished phones are not used phones. They are also not brand new phones. It only means that it is somewhere in between. Refurbished phones are cell phones that have been returned to the manufacturer because of some defect in the unit. Once these cell phones have been fixed, it is brought out in the market to be re-sold.

When a refurbished phone is out in the market the second time around, the cost of the unit is no longer the same as it was before when it was still brand new. The price is way much lower now thus making it more affordable for people who are looking for value for money mobile phones.

It should not happen but there could be instances wherein a refurbished phone might not be in a good condition upon receiving it or after several days you might have experienced a sudden defect in the phone. When this happens, it can cause some frustration because you already have a mindset that you have a new phone already and you have informed everyone of your new phone.

This type of case has to be returned to the distributor or reseller. However, before you return the cell phone, make sure that you check out first the conditions of the reseller or distributor. You need to make sure that they have a policy on returning goods and the conditions that come with it. There is no strict policy on this. Different resellers have different policies. What one may be offering, it might not be applicable to the other.

Look at the fine print of the deal. A good reseller or distributor states the terms and policies clearly. There is no grey area so you will feel comfortable, and you are assured that an action plan is in place in case things will not work out fine with the unit that you just purchased. Again, the policies for these resellers or dealers are not one and the same. Make sure that you follow the agreement stated on their website.

Some resellers or dealers will require you to return the handset in a complete form just like the way when you received it. The accessories and the other items that came with it should be returned, and a return policy should be stated as well in the website. You either get a replacement of the unit, or you get free credits in addition to the actual cost of the unit. Money-back guarantees depend on the resellers and not all offer this type of deal.

Getting a defective unit is nothing to fear about as long as before making that online purchase, you have understood the terms and conditions of the online store. Everything else will turn out fine.

Wireless Association is an online marketplace where you can find wireless industry association recommended wholesale cell phones

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