Simulasi rancangan material near-frictionless--T-REC-komunitas reptil-semarang--KSE-komunitas satwa eksotik

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Simulasi  rancangan  material near-frictionless

Date:

July 21, 2015

Source:

DOE/Argonne National Laboratory

Summary:

Scientists used the Mira supercomputer to identify and improve a new mechanism for eliminating friction, which fed into the development of a hybrid material that exhibited superlubricity at the macroscale for the first time. Researchers helped enable the groundbreaking simulations by overcoming a performance bottleneck that doubled the speed of the team's code.

Para ilmuwan menggunakan superkomputer Mira untuk mengidentifikasi dan memperbaiki mekanisme baru untuk menghilangkan gesekan , yang dimasukkan ke dalam pengembangan bahan hibrida yang pamerkan superlubricity di macroscale untuk pertama kalinya . Para peneliti membantu mengaktifkan simulasi terobosan dengan mengatasi hambatan kinerja yang dua kali lipat kecepatan kode tim .

............. While reviewing the simulation results of a promising new lubricant material, Argonne researcher Sanket Deshmukh stumbled upon a phenomenon that had never been observed before.

............. Sementara meninjau hasil simulasi dari bahan pelumas baru yang menjanjikan , peneliti Argonne Sanket Deshmukh menemukan sebuah fenomena yang belum pernah diamati sebelumnya .....more

Simulations lead
to design of near-frictionless material

Date:

July 21, 2015

Source:

DOE/Argonne National Laboratory

Summary:

Scientists used the Mira supercomputer to identify and improve a new
mechanism for eliminating friction, which fed into the development of a hybrid
material that exhibited superlubricity at the macroscale for the first time.
Researchers helped enable the groundbreaking simulations by overcoming a
performance bottleneck that doubled the speed of the team's code.

...........................

Argonne scientists used Mira to identify and improve a new mechanism for
eliminating friction, which fed into the development of a hybrid material that
exhibited superlubricity at the macroscale for the first time. Argonne
Leadership Computing Facility (ALCF) researchers helped enable the
groundbreaking simulations by overcoming a performance bottleneck that doubled
the speed of the team's code.

While reviewing the simulation results of a promising new lubricant
material, Argonne researcher Sanket Deshmukh stumbled upon a phenomenon that
had never been observed before.

"I remember Sanket calling me and saying 'you have got to come over
here and see this. I want to show you something really cool,'" said
Subramanian Sankaranarayanan, Argonne computational nanoscientist, who led the
simulation work at the Argonne Leadership Computing Facility (ALCF), a DOE
Office of Science User Facility.

They were amazed by what the computer simulations revealed. When the
lubricant materials--graphene and diamond-like carbon (DLC)--slid against each
other, the graphene began rolling up to form hollow cylindrical
"scrolls" that helped to practically eliminate friction. These
so-called nanoscrolls represented a completely new mechanism for
superlubricity, a state in which friction essentially disappears.

"The nanoscrolls combat friction in very much the same way that ball
bearings do by creating separation between surfaces," said Deshmukh, who
finished his postdoctoral appointment at Argonne in January.

Superlubricity is a highly desirable property. Considering that nearly
one-third of every fuel tank is spent overcoming friction in automobiles, a
material that can achieve superlubricity would greatly benefit industry and
consumers alike. Such materials could also help increase the lifetime of
countless mechanical components that wear down due to incessant friction.

Experimental origins

Prior to the computational work, Argonne scientists Ali Erdemir, Anirudha
Sumant, and Diana Berman were studying the hybrid material in laboratory
experiments at Argonne's Tribology Laboratory and the Center for Nanoscale
Materials, a DOE Office of Science User Facility. The experimental setup
consisted of small patches of graphene (a two-dimensional single-sheet form of
pure carbon) sliding against a DLC-coated steel ball.

The graphene-DLC combination was registering a very low friction
coefficient (a ratio that measures the force of friction between two surfaces),
but the friction levels were fluctuating up and down for no apparent reason.
The experimentalists were also puzzled to find that humid environments were
causing the friction coefficient to shoot up to levels that were nearly 100
times greater than measured in dry environments.

To shed light on these mysterious behaviors, they turned to
Sankaranarayanan and Deshmukh for computational help. Using Mira, the ALCF's
10-petaflops IBM Blue Gene/Q supercomputer, the researchers replicated the
experimental conditions with large-scale molecular dynamics simulations aimed
at understanding the underlying mechanisms of superlubricity at an atomistic
level.

This led to their discovery of the graphene nanoscrolls, which helped to
fill in the blanks. The material's fluctuating friction levels were explained
by the fact that the nanoscrolls themselves were not stable. The researchers
observed a repeating pattern in which the hollow nanoscrolls would form, and
then cave in and collapse under the pressure of the load.

"The friction was dipping to very low values at the moment the scroll
formation took place and then it would jump back up to higher values when the
graphene patches were in an unscrolled state," Deshmukh said.

The computational scientists had an idea to overcome this issue. They tried
incorporating nanodiamond particles into their simulations to see if the hard
material could help stabilize the nanoscrolls and make them more permanent.

Sure enough, the simulations proved successful. The graphene patches
spontaneously rolled around the nanodiamonds, which held the scrolls in place
and resulted in sustained superlubricity. The simulation results fed into a new
set of experiments with nanodiamonds that confirmed the same.

"The beauty of this particular discovery is that we were able to see
sustained superlubricity at the macroscale for the first time, proving this
mechanism can be used at engineering scales for real-world applications,"
Sankaranarayanan said. "This collaborative effort is a perfect example of
how computation can help in the design and discovery of new materials."

Not slippery when wet

Unfortunately, the addition of nanodiamonds did not address the material's
aversion to water. The simulations showed that water suppresses the formation
of scrolls by increasing the adhesion of graphene to the surface.

While this greatly limits the hybrid material's potential applications, its
ability to maintain superlubricity in dry environments is a significant
breakthrough in itself.

The research team is in the process of seeking a patent for the hybrid
material, which could potentially be used for applications in dry environments,
such as computer hard drives, wind turbine gears, and mechanical rotating seals
for microelectromechanical and nanoelectromechanical systems.

Adding to the material's appeal is a relatively simple and cost-effective
deposition method called drop casting. This technique involves spraying
solutions of the materials on moving mechanical parts. When the solutions
evaporate, it would leave the graphene and nanodiamonds on one side of a moving
part, and diamond-like carbon on the other side.

However, the knowledge gained from their study is perhaps even more
valuable, said Deshmukh. He expects the nanoscroll mechanism to spur future
efforts to develop materials capable of superlubricity for a wide range of mechanical
applications.

For their part, the Argonne team will continue its computational studies to
look for ways to overcome the barrier presented by water.

"We are exploring different surface functionalizations to see if we
can incorporate something hydrophobic that would keep water out,"
Sankaranarayanan said. "As long as you can repel water, the graphene
nanoscrolls could potentially work in humid environments as well."

Simulating millions of atoms

The team's groundbreaking nanoscroll discovery would not have been possible
without a supercomputer like Mira. Replicating the experimental setup required
simulating up to 1.2 million atoms for dry environments and up to 10 million
atoms for humid environments.

The researchers used the LAMMPS (Large-scale Atomic/Molecular Massively
Parallel Simulator) code to carry out the computationally demanding reactive
molecular dynamics simulations.

With the help of ALCF catalysts, a team of computational scientists who
work directly with ALCF users, they were able to overcome a performance
bottleneck with the code's ReaxFF module, an add-on package that was needed to
model the chemical reactions occurring in the system.

The ALCF catalysts, in collaboration with researchers from IBM, Lawrence
Berkeley National Laboratory, and Sandia National Laboratories, optimized
LAMMPS and its implementation of ReaxFF by adding OpenMP threading, replacing
MPI point-to-point communication with MPI collectives in key algorithms, and
leveraging MPI I/O. Altogether, these enhancements allowed the code to perform
twice as fast as before.

"With the code optimizations in place, we were able to model the
phenomena in real experimental systems more accurately," Deshmukh said.
"The simulations on Mira showed us some amazing things that could not be seen
in laboratory tests."

And with the recent announcement of Aurora, the ALCF's next-generation
supercomputer, Sankaranarayanan is excited about where this line of research
could go in the future.

"Given the advent of computing resources like Aurora and the wide
gamut of the available two-dimensional materials and nanoparticle types, we
envision the creation of a lubricant genome at some point in the future,"
he said. "Having a materials database like this would allow us to pick and
choose lubricant materials for specific operational conditions."

Contributors to the code optimization work include Nichols A. Romero, Wei
Jiang, and Chris Knight from the ALCF; Paul Coffman from IBM; Hasan Metin
Aktulga from Lawrence Berkeley National Laboratory (now at Michigan State
University); and Tzu-Ray Shan from Sandia National Laboratories.







Story Source:

The above post is reprinted from materials provided byDOE/Argonne
National Laboratory. The original item was written by Jim Collins. Note:
Materials may be edited for content and length.







Journal Reference:

1.   
D. Berman, S. A. Deshmukh, S. K. R. S. Sankaranarayanan, A. Erdemir, A. V.
Sumant. Macroscale superlubricity enabled by graphene nanoscroll
formation. Science, 2015; 348 (6239): 1118 DOI: 10.1126/science.1262024

http://www.sciencedaily.com/releases/2015/07/150721194001.htm

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Bakteri mulut dapat mengubah pola makannya, superkomputer mengungkapkan --T-REC semarang--komunitas reptil semarang

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.................

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www.trecsemarang2011.blogspot.com

minat gabung : ( menerima keanggotaan seluruh kota dan daerah di Indonesia )

08995557626

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KSE – KOMUNITAS SATWA EKSOTIK – EXOTIC PETS COMMUNITY-- INDONESIA

Visit Our Community and Joint W/ Us....Welcome All Over The World

www.facebook.com/groups/komunitassatwaeksotik/

 KSE = KOMUNITAS SATWA EKSOTIK

MENGATASI KENDALA MINAT DAN JARAK

KAMI ADA DI TIAP KOTA DI INDONESIA 

DETAIL TENTANG KSE-----KLIK : www.komunitassatwaeksotik-pendaftaran.blogspot.com 

GABUNG......... ( menerima keanggotaan seluruh kota dan daerah di Indonesia )

HUBUNGI   :  089617123865

.........................

 

Bakteri mulut dapat mengubah pola makannya, superkomputer mengungkapkan

Bakteri mulut dapat mengubah metabolisme mereka dalam penyakit versus kesehatan. Superkomputer Stampede dan Lonestar bandingkan ekspresi gen 160.000 gen dalam komunitas jaringan penyangga gigi yang sehat dan sakit. Penelitian ini membuka jalan bagi biomarker untuk memprediksi penyakit dari penyakit-penyakit yang luas seperti periodontitis, diabetes, dan penyakit Crohn.....read more

Mouth bacteria can change its diet, supercomputers reveal

Date:

August 12, 2014

Source:

University of Texas at Austin, Texas Advanced Computing Center

Summary:

Mouth bacteria can change their metabolism in disease versus health. The Stampede and Lonestar supercomputers compared gene expression of 160,000 genes in healthy and diseased periodontal communities. Research paves way for biomarkers to predict illness from wide-ranging diseases such as periodontitis, diabetes, and Crohn's disease.

...............................

Bacteria inside your mouth drastically change how they act when you're diseased, according to research using supercomputers at the Texas Advanced Computing Center (TACC). Scientists say these surprising findings might lead to better ways to prevent or even reverse the gum disease periodontitis, diabetes, and Crohn's disease.

Marvin Whiteley, professor of molecular biosciences and director of the Center for Infectious Disease at The University of Texas at Austin, led the study published in April 2014 in the journal mBio.

"What we were trying to figure out," said Whiteley, "is how do these bacteria act when you're healthy, and how do they act when they're in a diseased state. The really big finding is that they do act very differently."

Bacteria share nutrients, and one species will even feed on another as they constantly interact. "The thing that we found in this paper," said Whiteley, "is that this sharing, and how they interact with each other changes quite drastically in disease than it does in health."

UT Austin researchers used shotgun metagenomic sequencing, a non-targeted way to study the all the genetic material of the bacterial communities. Whiteley and colleagues analyzed the RNA collected with the Lonestar and Stampede supercomputers at TACC. They were awarded computing allocations through the University of Texas System Research Cyberinfrastructure initiative. The research was funded by grants from the National Institutes of Health, administered by the National Institute of Dental and Craniofacial Research.

It might come as a surprise that microbes, mainly bacteria, outnumber human cells in our body by 10 to 1. And scientists have identified 10,000 different species of bacteria that live inside each person. These microbial communities are collectively known as the human microbiome. That's according to a five-year, $115 million research effort that began in 2008 by the National Institutes of Health (NIH) called the Human Microbiome Project.

"The easiest way to think of it is just the collection of bacteria that are in or on your body," Whiteley said. "We think of it as not only the bacteria, but the genetic composition. What's their DNA? And from that we can infer what these bacteria might be doing for us."

Whiteley's lab started by isolating RNA from the plaque samples collected. Study co-author Keith Turner, a postdoctoral researcher in Whiteley's lab, explained. "RNA, for those who know about computers, is kind of like the RAM (random access memory), the working memory of the cell." The RNA sample acts like a memory image or 'core dump' to reveal the processes of the as-yet unknown bacterium it came from. And unfortunately, said Turner, you can't get a full picture of the activity because there are so many molecules in the sample.

"But what you do," Turner explained, "is get what you can and profile it by sequencing, using some recent technological advances. Then it's essentially a search problem."

Turner searched a metagenomic database, essentially a vast genetic clearing house sampled from the environment instead of lab grown. He looked for matches at the NIH's Human Microbiome Project. A match told what bacterium a gene came from in the sample, and Turner tallied each match. "The more it's thinking about a certain process, the more it seems to be important to it," said Turner. "The shotgun approach, as you might imagine, is very computationally intensive, which is why we turned to TACC for some of these problems."

How big were these problems?

Turner and colleagues chose 60 different species of bacteria to represent the total community. More than 160,000 genes were analyzed, yielding 28 to 85 million reads of RNA snippets, including about 17 million mRNA reads for each sample.

His main findings show that bacteria act differently when one is healthy compared to when diseased. "The main thing that they change when they go from health to disease is that they change their metabolism," Whiteley said. In other words, a species of bacteria that ate one thing, fructose for example, can switch to a different kind of sugar to feed on if diseased.

"The kind of thing that might have taken a desktop computer a week, two weeks to run we can run at TACC in just a couple of hours," Turner said. "Stampede allows us to use 6,400 desktop computers, all at the same time. There are a lot of problems in biology that can benefit from the supercomputing approach."

Whiteley found periodontitis interesting because it's one of the most prevalent diseases on the planet. "It's an interesting disease, because the same bacteria that are in your mouth when you're healthy are the same ones, more or less when you're sick," he said.

"What our study says is that it doesn't really matter what bacteria you have, because the communities are acting very similarly," Whiteley explained. "So a healthy community has this metabolism, no matter what the members are. And a diseased community has a very different metabolism, no matter what the members are. It's this conservation of a metabolic community. "

Whiteley compared what's happening under our gums to an ecosystem in the African savannah. The interactions among 'animals' is key. "You have lions, and you have leopards, and wildebeest, and all of these animals that are there. If you look at it as a whole community, it kind of makes sense. But if you were to only take a one-acre plot out of the African savannah and look at it, it may not make sense because there may not be a lion in that one acre. So trying to understand interactions, you need to take a much larger, bigger context. And that's what this study did," Whiteley explained.

According to science results from the Human Microbiome Project, a shift to more harmful bacteria in the community is linked to wide-ranging diseases such as periodontitis, diabetes, and Crohn's disease.

Whiteley said his research can help people by helping to develop biomarkers that predict if someone's going to get sick. "Can you actually come up with a very quick way to assess the behavior of the community quickly and say, are you on the progression of moving from health to disease, and then provide some sort of preventative measure when you get there," Whiteley explained.

Pathogenic bacterial communities that rewired themselves to be harmful might also be rewired for health. It's possible in theory, anyway, according to Whiteley.

"You can manipulate bacterial populations numerically very easily. You feed them something else. So you might be able to shift them back. These are some of the ideas that we've been thinking about in our lab that might be more pervasive as we move forward."

"Medicine is going to change a lot in the next 10 to 50 years. We're going to be thinking about these sort of questions a lot more, questions like what is your microbiome actually doing, and is that impacting why you're in the doctor's office," Whiteley said.

---

Story Source:

The above story is based on materials provided by University of Texas at Austin, Texas Advanced Computing Center. The original article was written by Jorge Salazar. Note: Materials may be edited for content and length.

---

Journal Reference:

1. P. Jorth, K. H. Turner, P. Gumus, N. Nizam, N. Buduneli, M. Whiteley. Metatranscriptomics of the Human Oral Microbiome during Health and Disease. mBio, 2014; 5 (2): e01012-14 DOI: 10.1128/mBio.01012-14

http://www.sciencedaily.com/releases/2014/08/140812163810.htm

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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