Tag Archives: metals

How To Make Solar Panels More Sustainable And Cheaper

An innovative way to pattern metals has been discovered by scientists in the Department of Chemistry at the University of Warwick in UK, which could make the next generation of  solar panels more sustainable and cheaperSilver and copper are the most widely used electrical conductors in modern electronics and solar cells. However, conventional methods of patterning these metals to make the desired pattern of conducting lines are based on selectively removing metal from a film by etching using harmful chemicals or printing from costly metal inks.

Scientists from the Department of Chemistry at the University of Warwick, have developed a way of patterning these metals that is likely to prove much more sustainable and cheaper for large scale production, because there is no metal waste or use of toxic chemicals, and the fabrication method is compatible with continuous roll-to-roll processing. Dr Ross Hatton and Dr Silvia Varagnolo have discovered that silver and copper do not condense onto extremely thin films of certain highly fluorinated organic compounds when the metal is deposited by simple thermal evaporation.

Thermal evaporation is already widely used on a large scale to make the thin metal film on the inside of crisp packets, and organofluorine compounds are already common place as the basis of non-stick cooking pans. The researchers have shown that the organofluorine layer need only be 10 billionths of a metre thick to be effective, and so only tiny amounts are needed. This unconventional approach also leaves the metal surface uncontaminated, which Hatton believes will be particularly important for the next generation sensors, which often require uncontaminated patterned films of these metals as platforms onto which sensing molecules can be attached.

To help address the challenges posed by climate change, there is a need for colour tuneable, flexible and light weight solar cells that can be produced at low cost, particularly for applications where conventional rigid silicon solar cells are unsuitable such as in electric cars and semi-transparent solar cells for buildings. Solar cells based on thin films of organic, perovskite or nano-crystal semiconductors all have potential to meet this need, although they all require a low cost, flexible transparent electrode. Hatton and his team have used their method to fabricate semi-transparent organic solar cells in which the top silver electrode is patterned with millions of tiny apertures per square centimetre, which cannot be achieved by any other scalable means directly on top of an organic electronic device.

This innovation enables us to realise the dream of truly flexible, transparent electrodes matched to needs of the emerging generation of thin film solar cells, as well as having numerous other potential applications ranging from sensors to low-emissivity glass” explains Dr Hatton from the Department of Chemistry at the University of Warwick.

The work is published in the journal Materials Horizons.

Source: https://warwick.ac.uk/

How To Reverse Vascular Disease In Kidney Failure

By loading a chelation drug into a nano-sized homing device, researchers at Clemson University have reversed in an animal model the deadliest effects of chronic kidney disease, which kills more people in the United States each year than breast or prostate cancer. When kidneys stop working properly, calcium builds up in artery tissue, leading to heart disease. Although nearly half a million Americans receive kidney dialysis, heart disease is the leading cause of death for people with chronic kidney disease.

Human kidney cross section on scientific background

The findings are very exciting scientifically, but also for the thousands of patients who could potentially benefit from this technology one day,” said Naren Vyavahare, professor of bioengineering at Clemson and the principal investigator of the research.

Chelation, a method of removing metals such as iron and lead from the body, has been used experimentally for some people with heart disease. The therapy is not approved by the Food and Drug Administration, but the National Institutes of Health has sponsored two large-scale, multi-center studies using ethylene diamine tetra-acetic acid, or EDTA, as chelation therapy for people with heart disease.

In clinical studies, EDTA is included in an infusion that circulates through the body; it’s systemic and non-specific. This method of chelation has shown good results in improving heart function, especially in diabetic patients, Vyavahare said. But EDTA infusion therapy is arduous (it requires 40 infusions over a period of a year), and it can cause side effects, including a depletion of calcium from the blood and from bone.

Now, in a paper published in Scientific Reports, a Nature publication, Vyavahare’s team describes how they developed an animal model that mimics a human’s chronic kidney disease. Animals were treated either with EDTA infusions, like in the NIH human trials, or with EDTA enclosed in a nanoparticle coupled with an antibody that seeks out damaged elastin. In animals that received the targeted therapy, calcium buildup was destroyed, without causing side effects, better than with EDTA infusions alone. Moreover, the calcification did not come back up to four weeks after the last injection, even though other signs of chronic kidney disease were present.

Source: http://newsstand.clemson.edu/

Self-Healing Coating Protects Metals From Corrosion

It’s hard to believe that a tiny crack could take down a gigantic metal structure. But sometimes bridges collapse, pipelines rupture and fuselages detach from airplanes due to hard-to-detect corrosion in tiny cracks, scratches and dents. A Northwestern University team has developed a new coating strategy for metal that self-heals within seconds when scratched, scraped or cracked. The novel material could prevent these tiny defects from turning into localized corrosion, which can cause major structures to fail.

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Localized corrosion is extremely dangerous,” said Jiaxing Huang, who led the research. “It is hard to prevent, hard to predict and hard to detect, but it can lead to catastrophic failure.” Huang is a professor of materials science and engineering in Northwestern’s McCormick School of Engineering.

When damaged by scratches and cracks, Huang’s patent-pending system readily flows and reconnects to rapidly heal right before the eyes. The researchers demonstrated that the material can heal repeatedly — even after scratching the exact same spot nearly 200 times in a row.While a few self-healing coatings already exist, those systems typically work for nanometer- to micron-sized damages. To develop a coating that can heal larger scratches in the millimeter-scale, Huang and his team looked to fluid. “When a boat cuts through water, the water goes right back together,” Huang said. “The ‘cut’ quickly heals because water flows readily. We were inspired to realize that fluids, such as oils, are the ultimate self-healing system.” But common oils flows too readily, Huang noted. So he and his team needed to develop a system with contradicting properties: fluidic enough to flow automatically but not so fluidic that it drips off the metal’s surface.

The team met the challenge by creating a network of lightweight particles — in this case graphene capsules — to thicken the oil. The network fixes the oil coating, keeping it from dripping. But when the network is damaged by a crack or scratch, it releases the oil to flow readily and reconnect. Huang said the material can be made with any hollow, lightweight particlenot just graphene. “The particles essentially immobilize the oil film,” Huang said. “So it stays in place.”

The study was published  in Research, the first Science Partner Journal recently launched by the American Association for the Advancement of Science (AAAS) in collaboration with the China Association for Science and Technology (CAST).

Source: https://news.northwestern.edu/

How To Shrink Objects To The Nanoscale

MIT researchers have invented a way to fabricate nanoscale 3-D objects of nearly any shape. They can also pattern the objects with a variety of useful materials, including metals, quantum dots, and DNA.

MIT engineers have devised a way to create 3-D nanoscale objects by patterning a larger structure with a laser and then shrinking it. This image shows a complex structure prior to shrinking.

It’s a way of putting nearly any kind of material into a 3-D pattern with nanoscale precision,” says Edward Boyden, the Y. Eva Tan Professor in Neurotechnology and an associate professor of biological engineering and of brain and cognitive sciences at MIT. Using the new technique, the researchers can create any shape and structure they want by patterning a polymer scaffold with a laser. After attaching other useful materials to the scaffold, they shrink it, generating structures one thousandth the volume of the original.

These tiny structures could have applications in many fields, from optics to medicine to robotics, the researchers say. The technique uses equipment that many biology and materials science labs already have, making it widely accessible for researchers who want to try it. Boyden, who is also a member of MIT’s Media Lab, McGovern Institute for Brain Research, and Koch Institute for Integrative Cancer Research, is one of the senior authors of the paper, which appears in the Dec. 13 issue of Science. The other senior author is Adam Marblestone, a Media Lab research affiliate, and the paper’s lead authors are graduate students Daniel Oran and Samuel Rodriques.

As they did for expansion microscopy, the researchers used a very absorbent material made of polyacrylate, commonly found in diapers, as the scaffold for their nanofabrication process. The scaffold is bathed in a solution that contains molecules of fluorescein, which attach to the scaffold when they are activated by laser light.

Using two-photon microscopy, which allows for precise targeting of points deep within a structure, the researchers attach fluorescein molecules to specific locations within the gel. The fluorescein molecules act as anchors that can bind to other types of molecules that the researchers add.

You attach the anchors where you want with light, and later you can attach whatever you want to the anchors,” Boyden says. “It could be a quantum dot, it could be a piece of DNA, it could be a gold nanoparticle.” “It’s a bit like film photography — a latent image is formed by exposing a sensitive material in a gel to light. Then, you can develop that latent image into a real image by attaching another material, silver, afterwards. In this way implosion fabrication can create all sorts of structures, including gradients, unconnected structures, and multimaterial patterns,” Oran explains.

Source: http://news.mit.edu/