segunda-feira, 6 de julho de 2015

Graphene coating boosts battery performance

 

 

Jul 6, 2015

Image illustrating the battery capacity of a mobile phone


Extra charge: graphene and silicon can increase battery capacity

The capacity of a lithium-ion battery can be nearly doubled by using an anode made from tiny nanoparticles of silicon wrapped in several layers of graphene. Researchers from South Korea – including electronics giant Samsung – have found that the graphene coating boosts the electrical conductivity of the particles and stops them from being damaged as their volume expands when the battery is charged. The scientists describe their work as "a meaningful step" towards the development of commercial batteries with silicon anodes.

Ubiquitous in portable electronics, rechargeable lithium-ion batteries consist of two electrodes – anode and cathode – separated by an electrolyte. When the battery is being charged with electrical energy, lithium ions move from the cathode through the electrolyte to the anode, where they are absorbed into the bulk of the anode material.

Expansion and contraction

When the battery is discharged, lithium ions come out of the anode and return to the cathode. This makes the anode first expand and then contract, which can damage the anode over repeated charge/discharge cycles. Anodes made from graphite, though, are resistant to this damage, which is why this material has been used in commercial batteries for three decades.

As portable devices become more energy-hungry, however, researchers have sought to boost the amount of energy that can be stored in lithium-ion batteries by developing anodes made from silicon. As well as being cheap and easy to work with, silicon can absorb 10 times more lithium ions per unit mass than graphite. Unfortunately, the volume of silicon expands by a factor of four when it absorbs lithium, which makes the silicon anodes prone to fracture and failure.

Cracking and coating

One way round this problem is to make the anode from an agglomeration of tiny spheres of silicon – each about 100 nm diameter – that are more resistant to cracking. But this approach also has its own challenges. Silicon is a semiconductor and to be an effective anode it must be coated with an electrical conductor. This coating must also remain intact as the nanospheres expand and contract.

Now Mark Rümmeli and colleagues at the Institute for Basic Science in Korea, at Samsung and at the Korea Advanced Institute of Technology have devised a way to coat silicon nanoparticles with multiple layers of graphene. Graphene is a layer of carbon just one atom thick that is both a good electrical conductor and an extremely strong material. These two properties combine to make the coated nanoparticles very good conductors that are able to increase in size without damage to the coating or to the nanoparticles.

An important challenge for Rümmeli and colleagues was how to coat silicon with graphene without creating a thin layer of silicon carbide between the two materials. This is because silicon carbide is an electrical insulator and also inhibits the flow of lithium ions. The team achieved silicon-carbide-free growth by heating the nanoparticles in the presence of methane and carbon dioxide.

High conductivity

Thanks to the graphene coating, a powder sample of nanoparticles has a conductivity that is 100 million times greater than a powder sample of uncoated particles. The team then made anodes from the coated nanoparticles and tested them in otherwise standard lithium-ion batteries. During the first charge–discharge cycle they found that the batteries held 1.8 times more energy than a battery with a conventional graphite anode. After 200 cycles, the batteries were still able to store 1.5 times more energy than a conventional device.

When the team took a closer look at individual nanoparticles using an electron microscope, the researchers found that each layer of graphene did not completely encapsulate a nanoparticle. This allowed the graphene layers to slide across each other as the nanoparticle grew in size, thereby creating an expandable shell. Rümmeli told physicsworld.com that a similar sliding effect has been seen in multiwalled carbon nanotubes – rolled up sheets of graphene – which can extend telescopically.

The team also believes that the sliding is offset by an inward "clamping" force that maintains the integrity of the graphene coating and reduces cracking in the nanoparticles. The incomplete layers also provide paths for the lithium ions to travel through the graphene coating to reach the anode.

The research is described in Nature Communications.

Fitness for less: Low-cost ways to shape up

 

 

 

Want to work out but think you can't afford it? Think again. Consider these low-cost alternatives to a pricey gym membership.

By Mayo Clinic Staff

If the only thing keeping you from starting a fitness program is the cost of a gym membership, here's good news. You don't need to join a gym to take physical activity seriously. Plenty of low-cost alternatives can help you get fit without breaking your budget. These tips can help you get started.

Take advantage of everyday opportunities

You don't need a gym or special equipment for an aerobic workout. With a little foresight, activities you may take for granted can become part of your fitness routine.

  • Step it up. Take a brisk walk every day, whether it's in your neighborhood or a local mall. Take the stairs instead of the elevator or make a full workout of climbing the stairs. Sneak in extra steps whenever you can by parking farther away from your destination.
  • Make housework a workout. Mow the lawn, weed the garden, rake the leaves or shovel the snow. Even indoor activities such as vacuuming and scrubbing count as a workout if you increase your heart rate.
  • Play with your kids. If you have children, don't just watch them play. Join them for a game of tag or kickball. Walk them to the park. Dance. Take a family bike ride. Go to a community pool. Even if you don't swim, you can enjoy time in the water or walk in the shallow end. Do your kids play video games? If so, plug in with them and swing a virtual tennis racket or do a little boxing.
Improvise by using household items or your body weight

If you'd rather not spend a penny on exercise equipment, use ordinary household items or your body weight for various upper and lower body exercises:

  • Canned goods. Many canned goods can serve double duty as hand weights.
  • Chair or step stool. Use a chair for support when doing exercises such as leg curls. A low, sturdy step stool can become exercise equipment if you use it for step training — an aerobic exercise resembling stair climbing.
  • Use your body. You don't need to go to the gym and lift weights to increase your muscular fitness. Use your body weight to do weight training exercises and resistance training.

April 17, 2015

References

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The North Sea Abloom

 

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Despite its cold waters and harsh winds, the North Sea is a fertile basin for phytoplankton blooms. The drifting, plantlike organisms tend to be most abundant in late spring and early summer due to high levels of nutrients in the water and increasing sunlight. The intense winds blowing over the relatively shallow North Sea causes a lot of vertical and horizontal mixing that brings nutrients to the surface, as does runoff from European rivers.

This image, acquired on June 11, 2015, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, shows a mass of phytoplankton blooming between Denmark, the United Kingdom, and Germany. As compared to a June 6 image showing a different stage of the bloom cycle, areas of concentrated phytoplankton are smaller and most have the milky color characteristic of coccolithophores; there are few to no green areas. The change could be due to the short life span of phytoplankton—two to six days—and differences between the species. Some outlast others because of their ability to survive at lower nutrient levels.

Some researchers have found that numbers of plankton can actually begin to increase in the middle of winter, when growth conditions would seem to be at their worst. Studies suggest that winter storms churn the ocean and cause deep water mixing. This water mixing allows for phytoplankton to grow and live at depth without being spotted by their predators. When spring arrives, phytoplankton can fully bloom because not only are the nutrients available, but there is a longer period of sunlight.

More information and images: NASA's Earth Observatory

Image Credit: NASA Earth Observatory images by Jesse Allen, using data from the Level 1 and Atmospheres Active Distribution System (LAADS)
Caption: Rachel Carlowicz with Mike Carlowicz, interpretation insight provided by Mike Behrenfeld, Oregon State University, and Jochen Wollschläger, Helmholtz-Zentrum Geesthacht

Last Updated: July 6, 2015

Editor: Sarah Loff

Australia's vast geothermal energy resources represent thousands of years worth of untapped power

 

 

Temperature readings taken in existing oil and gas bore holes indicate a huge amount of geothermal energy below the surface of Australia.

Temperature readings taken in existing oil and gas bore holes indicate a huge amount of geothermal energy below the surface of Australia. (Credit: Australian Geothermal Energy Association)

Australia is sitting on top of some of the world's most potent geothermal energy sources, according to government estimates. Just one percent of the hot rock energy less than 5 km under the surface would be enough to meet the whole country's entire power needs for 26,000 years if it was tapped. So why aren't we seeing more movement on it?

Geothermal energy is a very handy, virtually inexhaustible clean energy source for those areas lucky enough to find themselves on top of it. Massive amounts of hot rock just below the Earth's surface can be used to heat water and drive steam turbines for reliable electricity generation with virtually no emissions or environmental impact.

Where wind and solar tend to generate power at inconvenient or uncontrollable times, geothermal can be easily regulated and is ready to go 24/7. Surveys testing the available heat in existing bore holes down to a depth of 5 km (3 miles) below the surface indicate that Australia is sitting on some seriously large hot rock resources, as shown in our lead image.

So why is this enormous resource apparently so underdeveloped?

Part of the answer is geographic. Much of Australia's hot rock is simply not conveniently located close to major cities. The big red splotch of prime red geothermal activity to the centre right of the map is more or less on top of a large, barren desert area several hundred kilometres from Sydney or Adelaide, and large scale power transmission can be an expensive proposition.

Another part is geological. Australia has a ton of hot rock, but not a lot of the highly porous rock that makes for easy power extraction. To generate power, you need to be able to pump large amounts of water into a deep rock hole and let the water filter through pores and cracks in the rock, picking up heat as it goes, and then pump the heated water back to the surface on the other side.

Much of Australia's hot rock isn't porous enough to let a good flow of water through, which means in order to set up a geothermal power plant, engineers need to forcibly crack the rock, slowly pumping water into an underground rock reservoir at high pressure, to create the appropriate kinds of cracks and channels. It's a costly process, and it's a bit hit and miss.

A final problem facing all renewable energy sources may be political. While the fossil fuel energy industries enjoy some AU$4 billion in direct subsidies and tax breaks, the Australian government has allocated just AU$50 million to geothermal development.

On top of that, the current conservative government has succeeded in slashing Australia's 2020 renewable energy target from 41,000 gigawatt hours by about 20 percent down to 33,000 – and managed to include the burning of scrap wood in the "renewable" target at the same time.

Australian Prime Minister Tony Abbott has made his beliefs on renewable energy clear, saying "Coal is good for humanity… Essential to the prosperity of the world," while describing wind farms as "ugly… noisy and they may have all sorts of other impacts… It's right and proper that we're having an enquiry into the health impacts of these things." Abbott's treasurer Joe Hockey has also described wind generators as "utterly offensive."

Still, the Australian Geothermal Energy Association views both State and Federal governments as "very supportive" to the handful of operators currently working on developing geothermal projects. So perhaps there's a cleaner future in store for a country that currently ranks as the 10th highest carbon polluter per capita in the world.

By Loz Blain - July 5, 2015

source:gizmag.com

ADAMAAS smart glasses to assist elderly and disabled in everyday tasks

 

 

We've seen various head-mounted wearables, such as the Motorola HC1, Golden-i and the AITT system, which are designed to give industrial workers or military personnel a helping hand in carrying out highly specialized tasks. But what about the elderly or disabled that struggle with everyday tasks? That's the niche a pair of smart glasses developed through the "Adaptive and Mobile Action Assistance in Daily Living Activities" (ADAMAAS) project are intended to fill.

The ADAMAAS glasses are designed to determine what the wearer is doing, such as cooking a meal, and not only provide context-appropriate assistance in the form of text, visuals or avatars on a virtual plane in the wearer's field of view, but also react when a mistake is made. The goal is to allow them to continue working on a task while receiving instructions on how to do it better and correct mistakes as they happen.

Unlike other smart glasses, such as Google Glass, the ADAMAAS glasses are particularly targeted at elderly and disabled people, and will ultimately provide directions for basic tasks, like how to bake a cake or brew a pot of coffee, as well as more complex tasks, such as fixing a bicycle or practicing yoga.

The ADAMAAS project is being conducted at the Cluster of Excellence Cognitive Interactive Technology (CITEC) at Bielefeld University in Germany. The group recently received €1.2 million (US$1.3 million) in funding from the German Federal Ministry for Education to further development of the glasses.

“In this project, different technologies are being combined, including memory research, eye tracking and vital parameter measurements (such as pulse or heart rate), object and action recognition (Computer Vision), as well as Augmented Reality (AR) with modern diagnostics and corrective intervention techniques,” explains CITEC researcher Thomas Schack.

It's a different approach to the wearable space, taking a diagnostic system that is usually stationary and making it mobile, while also integrating monitoring technology that enables reaction to and individualized support for the user's actions in real time. This could mean huge things for people who face challenges with everyday tasks but who want to remain independent.

Source: Bielefeld University

Kepler Energy reveals plans for tidal energy scheme in Bristol Channel

 

 

Kepler Energy's Transverse Horizontal Axis Water Turbine (THAWT) uses a stressed truss configuration

Kepler Energy's Transverse Horizontal Axis Water Turbine (THAWT) uses a stressed truss configuration

With its large tidal range, Britain's Bristol Channel has a huge potential for generating tidal electric power. The problem is that, until now, schemes for tapping that power have required building dams and barrages so gigantic they would have given even the most wild-eyed Victorian engineer pause. As a more economical alternative, Kepler Energy has announced plans for a 30 MW tidal energy fence to be built in the Channel. With an estimated cost of £143 million (US$223 million), the underwater fence would be built in the water somewhere along the line between Aberthaw and Minehead and could be operational by 2021.

According to some estimates, if the tides that flow in and out of the Bristol Channel could be properly harnessed, they could supply up to five percent of Britain's energy needs. It's a challenge that has attracted engineers for over a century, but while on paper there's a tremendous amount of energy waiting to be tapped, a viable plan of how to actually go about it has proven elusive.

The main stumbling block is the nature of tidal power technology. Most conventional systems rely on horizontal axis turbines. This is like an underwater wind turbine and, like its terrestrial counterparts, it has severe limitations as to where it can be placed and under what conditions it can generate a practical amount of energy without ripping itself apart. Larger outputs require larger blades, which is a tricky enough problem with wind turbines, but water turbines tend to cavitate, which reduces efficiency and damages the turbine, so there's an upper limit to how big the machine can get. Because of these various factors, horizontal axis turbines are confined to deep waters over 30 m (98 ft) deep and tidal flows of over 2.5 m/s (8.2 ft/s).

The top alternative is Dynamic Tidal Power (DTP). This requires large barrages thrusting many miles out into the sea to channel the tide toward the turbines. Theoretically, such an installation could produce 10 to 15 GW of energy with a 40 to 50 km (25 to 31 mi) wall, but it's a massive investment and it has to be built first before the engineers can determine how well it works, so there's a high level of uncertainty.

For its project, Kepler Energy is using its Transverse Horizontal Axis Water Turbine (THAWT) technology. Developed by Oxford University’s Department of Engineering Science, it's designed for deployment in shallower, lower velocity tidal waters. It's based on a stressed truss configuration with carbon composite hydrofoil blades. According to Kepler, this simple design with a minimum of moving parts allows the dynamos and other electrical equipment to be installed in dry columns. In this, the generating units consist of two sets of blades sitting on three columns with a single generator between them.

Kepler regards the Bristol channel as ideal for the installation and plans for the turbines to be set up as a subsurface tidal fence 1 km (0.6 mi) long, while future fences could be over 10 km (6.2 mi) long. The idea is that the fence causes the current to back up against it as it tries to flow past. This phenomenon, known as blockage, produces a head of water that increases the efficiency of the turbines. Blockage increase with the length of tidal fence, so the longer the fence, the greater the output by each turbine.

According to Kepler, the new system does not require specialist vessels to overlook them, and can operate over a wider range of sea conditions than the alternatives. The Kepler blades cover a much greater area than horizontal axis turbines with much less depth needed. They also claim that the simplicity of the design makes it much less expensive than more conventional designs.

Kepler Energy is currently seeking funding for the project as it moves into the development and planning phases, which includes a rigorous environmental assessment. It has presented its plans to the Department of Energy & Climate Change, the Welsh Government, The Crown Estate, and Bristol City Council, and plans to start a stakeholder consultation program

“As our tidal technology can operate in lower velocity tidal waters, there is greater scope for its deployment in the UK and overseas." says Peter Dixon, Chairman of Kepler Energy. "It means that we can achieve greater economies of scale as our projects are deployed. We can happily co-exist with tidal lagoons, and the power peaks will occur at different stages of the tide, meaning that the combined output into the grid will be more easily manageable. In addition, our levelized costs of production will be in the range £100 to £130 (US$156 to US$202) per MWh for utility scale production, so costs will be cheaper than lagoons and in time we will be cheaper than offshore wind generation. Furthermore, investment risk is manageable since turbines are added incrementally to form the fence, with each one generating revenue as it is added.”

 

Source: Kepler Energy

Elastic, wound-healing hydrogel activated by light

 

 

Bioengineers have developed a new protein-based gel (not pictured) that mimics many of the properties of elastic tissue when exposed to light

Bioengineers have developed a new protein-based gel (not pictured) that mimics many of the properties of elastic tissue when exposed to light (Credit: Shutterstock)

Hydrogels have huge potential in the field of biomedicine, but aren't without their shortcomings in their existing form. These tiny polypeptide chains are championed for their many possible applications. Indeed, in the last few years alone we've seen advances that suggest they could find use in generating new heart tissue, fighting off superbugs and the controlled release of anti-inflammatory drugs. But researchers have now developed a hydrogel that mimics the elasticity of human tissue and can be activated by exposure to light, claiming it could offer safer means of repairing wounded tissue.

In order to bestow them with enough strength and stability, some hydrogels are treated with chemical compounds, which can then over time see them degrade into harmful materials. Bioengineers at Brigham and Women's Hospital (BHW) in Boston say they have overcome this problem by creating a hydrogel that becomes stronger only once it is exposed to light.

They call their new material a photocrosslinkable elastin-like polypeptide-based (ELP) hydrogel. As the gel is exposed to light, its molecules bind together to create a mechanical stability, so much so that it can endure more stretching than that experienced by arterial tissue in the body. Perhaps even more promising was the fact that they could dictate both the level of swelling and strength of the material, suggesting it could prove to have a number of uses.

"Our hydrogel has many applications: it could be used as a scaffold to grow cells or it can be incorporated with cells in a dish and then injected to stimulate tissue growth," says Nasim Annabi, PHD at BHW's Biomedical Engineering Division. "In addition, the material can be used as a sealant, sticking to the tissue at the site of injury and creating a barrier over a wound."

The gel was found to be consumed by naturally-occurring enzymes over time and had no toxic effects on living cells in the lab. The team also discovered that mixing the gel with silica nanoparticles gave it the ability to more effectively prevent bleeding, something that could allow better protection of a wound and stop bleeding with a single treatment.

The scientists say that more pre-clinical studies are required to test the gel's properties and safety before human trials will be possible.

The research was published in the journal Advanced Functional Materials.

Source: Brigham and Women's Hospital

Detecting eye diseases using a Smartphone

 

 

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Researchers at the Medical and Surgical Center for Retina developed software that detects eye diseases such as diabetic macular edema using a smartphone. The system is aimed at general physicians who could detect the condition and refer the patient to a specialist.

The software was developed in collaboration with biomedical engineers from the ITESM and uses the camera of the phone to detect any abnormality in the thickness of the retina. "The idea is to detect and prevent diseases in general practice. We are not replacing the specialist, we want to know which patients have a disease and make an early detection," says Dr. Juan Carlos Altamirano Vallejo, medical director of the Medical and Surgical Center for Retina.

He adds that the technology is designed for general physicians, "who support the health system in Mexico and, even without in-depth knowledge of ophthalmology, can, with this tool, detect certain abnormalities and send the patient to the specialist."

Using the software will reduce costs and streamline the Mexican health system. With just having the app on the cell phone and focusing the camera on the eye, immediate results will be obtained. "We start off the fact that it is much cheaper to prevent than to cure blindness."

The app also has utility in rural communities, where expertise areas such as ophthalmology have not arrive yet because equipment to detect these diseases are expensive and so far only the visiting specialist can do this kind of diagnosis.

"It will help those that when they go to the eye doctor are already blind, we needed to go a step back, to know who is at risk and needs to go to a specialist. Not wait for a doctor," says Altamirano Vallejo.

Software development has been satisfactory and is expected to soon be marketed and incorporated the basic health system.

Altamirano Vallejo comments that the Medical and Surgical Center for Retina is a small company with just ten employees dedicated to ophthalmology and retina special medical care. It it also dedicated to biomedical and pharmaceutical research, to develop diagnostics and equipment, applicable to society. "We want to give back to our community everything it gives to us, trying to pay the mortgage we all have with Mexico."


Story Source:

The above post is reprinted from materials provided by Investigación y Desarrollo. Note: Materials may be edited for content and length.


Southwest of the USA in Black and White

 

Posted: 05 Jul 2015 04:00 AM PDT

Le photographe américain Bobi Dojcinovski s’est rendu dans le Sud-Ouest des Etats-Unis. Il nous offre une série intitulée « The US Southwest in Black and White », dans laquelle il retrace son périple à travers de superbes clichés en noir et blanc. L’artiste met en lumière l’immensité des espaces traversés à l’aide de magnifiques contrastes.

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domingo, 5 de julho de 2015

Biomagnetic Imaging–excerpts

 

 

Summary:

The biomagnetic imaging program develops standards, measurement methods, and new magnetic imaging modalities for biomedical and environmental applications.

Description:

Biomagnetic Imaging Standards: Develops calibration structures (phantoms) and validates quantitative imaging protocols for magnetic resonance imaging (MRI); focusing on standards for cancer, brain, and multimodal imaging.

NIST/SMRM system phantom

biomagnetic imaging phantoms

Figure 1. NIST MRI system, diffusion, and breast phantoms

Magnetic Nanoagents: Develops nanofabricated agents that can sense and report local properties including , agent ID, location, temperature, pH.

microfabricated smart agents

Figure 2. (a) Microfabricated smart agents that have water proton resonance shifts to indicate particle ID, local temperature or pH. (b) Rare-earth doped iron oxide nanoparticle imaging agents.

New magnetic imaging modalities: Developing ultralow field (ULF) MRI, magnetic resonance elastography, electron paramagnetic resonance imaging.

www.nist.gov