Synthetic porous material mimics behaviour of proteins
Researchers from Liverpool University have synthesised a new porous material that exhibits similar structural change and chemical activity to proteins. Described in the journal Nature, the flexible crystalline porous material consists of metal ions and small peptide molecules. It features tiny pores less than one nanometre in diameter and can adapt its structure in response to its environment to perform different chemical tasks, just like proteins. The researchers claim this is the first time a synthesised material has been developed that exhibits these type of features. Porous materials are widely used in industry as catalysts for the production of fuels and chemicals and in environmental remediation technologies as adsorbers for the removal of harmful compounds from air and water. However, these materials are rigid, unlike the proteins found in living systems. The innovation at the core of the work was to integrate protein-like flexibility into the structure of synthetic porous materials, giving them the ability to perform different tasks in different environments. The new material can be transformed from one structure to another by changes in its chemical environment. This allows it to perform a chemical process, such as taking up a particular molecule from its surroundings, in response to an imposed change in the surrounding solution.
US developed technique turns smartphones into rapid radiation detectors
Researchers from North Carolina State University have developed a new technique that turns smartphones and other electronic devices into radiation detectors. According to the group, the technique could be used to triage medical cases in the event of a radiological disaster and offers a far more rapid solution than conventional approaches to testing. The approach relies on testing crystalline insulators found in everything from thumb drives to smartphones. During use, the insulator is removed from its electronic device and cleaned. The sample is then placed in a thermally stimulated luminescence reader, which collects spectra relating to the number of electrons found in the flaws inherent to the sample's crystalline structure. That spectral data is then fed into a custom algorithm that calculates the sample's radiation exposure. Because the technique is high-throughput, accurate and precise, it can adequately assess an individual's exposure in about an hour. Prior methods can take weeks. A paper on the research titled 'Retrospective dosimetry at the natural background level with commercial surface mount resistors', is published in the journal Radiation Measurements.
Perovskite photovoltaics fine-tuned with new approach to material design
The performance of perovskite solar cells could be improved with a new approach to designing materials developed by UK universities. Perovskite solar cells are a photovoltaic technology with a power conversion efficiency over 20%, but their performance is hindered by ion defects that can move around and affect the internal electric environment within the cell. The perovskite material absorbs light to create an electronic charge and helps to extract the charge into an external circuit before it is lost to recombination. The majority of detrimental recombination can occur in different locations within the solar cell. In some designs it occurs predominantly within the perovskite, while in others it happens at the edges of the perovskite where it contacts adjacent materials called transport layers. Researchers from the Universities of Portsmouth, Southampton and Bath have now developed a way to adjust the properties of the transport layers to encourage the ionic defects within the perovskite to suppress recombination and encourage more efficient charge extraction. The researchers suggest that PSCs made using transport layers with low permittivity and doping are more stable than those with high permittivity and doping. These cells reportedly show reduced ion vacancy accumulation within the perovskite layers, which has been linked to chemical degradation at the edges of the perovskite layer.
Cartilage inspires new durable material for structural batteries
Researchers at the University of Michigan have developed a new type of durable material similar to a cartilage that could be used in structural batteries. Incorporating batteries into the structure of electric vehicles and drones has the potential to reduce weight and extend range. However, placing a battery into the bumper of a car or the wing of drone has obvious safety implications. Published in the journal ACS Nano, the research describes a rechargeable zinc battery with a cartilage-like solid electrolyte that is resistant to damage. Zinc is an established structural and battery material, but the rigid dendrites it forms on repeated recharge cycles have seen the metal largely confined to single-use batteries. To overcome the dendrite problem, the team developed a solid electrolyte from a composite of branched aramid nanofibres (BANFs) and poly(ethyleneoxide). Based on the structure of cartilage, the BANFs mimic the tissue's tough collagen and resist penetration from dendrites, while the poly(ethyleneoxide) replicates the cartilage's softer components and allows zinc ions to flow between the battery's two electrodes. According to the research, the prototype battery can run for more than 100 cycles at 90% capacity. As secondary batteries on drones, the zinc cells can extend the flight time by 5 to 25%, depending on the battery size, mass of the drone and flight conditions.
Two-dimensional materials may catalyse performance of promising lithium-air batteries
Lithium-air batteries are seen as one of the most promising technologies for future energy storage applications. Capable in the theory of storing 10 times more energy than lithium ion batteries and much lower in weight, they are still in development, with their stability and efficiency still not matching expectations. Battery researchers are trying to find catalysts that can increase the rate of the chemical reactions inside the battery, which increases their ability to hold and discharge energy. Engineers at the University of Illinois at Chicago are working on two-dimensional compounds of transition metals - the elements that occupy the central block of the periodic table, which tend to have a large number of electrons per atom that are capable of becoming involved with bonding and electrical activity - with non-metals. In the journal Advanced Materials, the researchers describe how a type of compound called transition metal dichalcogenides enabled lithium-air batteries to hold 10 times more energy than batteries using traditional catalysts. Chalcogenides are compounds incorporating elements of group 16 in the periodic table, including oxygen, sulphur, selenium and tellurium.
Liquid resin 3D printing process 100 times faster than other techniques claim researchers
A new 3D printing technique that uses light to produce complex shapes from a vat of liquid resin is up to 100 times faster than conventional 3D printing processes, claim its developers at the University of Michigan. The method - which uses two lights to control where a curable liquid resin hardens and solidifies and where it stays fluid - has so far been used to print a variety of complex three dimensional demonstration shapes including a lattice, a toy boat and a block letter M. The group claims that the technique overcomes the limitations of earlier so-called vat-printing efforts, which encountered problems with the resin solidifying on the window that the light shines through, stopping the print job just as it gets started. One earlier solution to this problem was a window that lets oxygen through, which penetrates into the resin and halts the solidification near the window, leaving a film of fluid that will allow the newly printed surface to be pulled away. But because this gap is only about as thick as a piece of transparent tape, the resin must be very runny to flow fast enough into the tiny gap between the newly solidified object and the window as the part is pulled up. This has limited vat printing to small, customised products. By replacing the oxygen with a second light to halt solidification, the team can produce a much larger gap between the object and the window, thus allowing resin to flow in thousands of times faster.