« DOE BETO hosting alternative aviation fuel workshop | Main | ExxonMobil and Princeton select five energy research projects; including batteries and solar » Proton conduction is key to devices such as proton exchange membrane fuel cells (PEMFCs); the performance-limiting component in PEMFCs is often the proton exchange membrane (PEM). In the search for more effective PEMs, reseachers have looked to porous solids such as metal-organic frameworks (MOFs) or covalent organic frameworks. With these, the proton conduction properties can be fine-tuned by controlling crystallinity, porosity and chemical functionality. To maximize proton conduction, three-dimensional conduction pathways are preferred over one-dimensional pathways, which prevent conduction in two dimensions. Researchers led by a team at the University of Liverpool (UK) now report in an open-access paper in the journal Nature Communications that they have developed crystalline porous molecular solids where the proton transport occurs in 3D pathway by virtue of the native channel structure and topology. The development could lead to the design of more effective fuel cell materials, including high-temperature PEMFCs. In principle, the rational design of architecture in crystalline porous molecules allows us to tune proton conductivity and improve our understanding of proton conduction mechanisms, as relevant to both materials science and biology. However, there are few examples of proton conduction in porous organic molecular solids. … One limitation of proton conduction in MOFs is the tendency for directional proton transport, which in turn arises from the low-dimension pore structures in most frameworks tested2. Even in the few 3D proton-conducting MOFs that are known, the protons were found to be transported in 1D channels in most cases. 3D proton transport is more favourable for application in PEMs, and hence there have been attempts to enhance proton mobility in MOFs by introducing defects or by decreasing the crystallinity. Here we present an alternative strategy, which is to develop crystalline porous molecular solids where the proton transport occurs in 3D pathway by virtue of the native channel structure and topology. We demonstrate this concept for a range of crystalline porous organic cages. For a neutral imine cage, CC3, the proton conductivity is relatively low under humid conditions, despite the hydrated 3D diamondoid pore network in the material. However, when a related amine cage, RCC1 was transformed into its crystalline hydrated salt (H RCC1)12+·12Cl−·4(H O), the proton conduction was improved by a factor of over 150. Indeed, the proton conductivity of 1 is comparable to pelletized proton-conducting MOFs. This was rationalized using both computer simulations and quasi-elastic neutron scattering (QENS) to elucidate the proton transport mechanism. We also explain the influence of the counter anions in the protonated cage salts, which act to ‘gate’ the proton conduction. The researchers synthesized molecules that enclose an internal cavity, forming a porous organic cage into which other smaller molecules can be loaded, such as water or carbon dioxide. When the cages form solid materials, they can arrange to form channels in which the small guest molecules can travel from one cage to another. The material forms crystals in which the arrangement of cages is very regular. This allowed the researchers to build an unambiguous description of the structure using crystallography. The molecules are also soluble in common solvents, which means they could be combined with other materials and fabricated into membranes (Nafion, for example). The Liverpool researchers measured the protonic conductivity of these porous organic cages after loading the channels with water, to assess their viability as PEM materials. The cages exhibited proton conductivities of up to 10-3 S cm-1, which is comparable to some of the best porous framework materials in the literature. In collaboration with researchers from the University of Edinburgh, Center for Neutron Research at National Institute of Standards and Technology (NIST), and Defence Science and Technology Laboratory (DSTL), they used a combination of experimental measurements and computer simulations to build a rich picture of how protons are conducted by the cage molecules. Two distinctive features of the proton conduction in organic cage crystals were highlighted as design principles for future PEM materials. First, the cages are arranged so that the channels extend in three dimensions. This means that the movement of the protons is not limited to a particular direction, as in the case of many porous materials tested so far. Second, the cages direct the movement of the water molecules, which means that protons can be passed between them quickly. Also, the cages are flexible enough to allow the water to reorganize, which is also important when protons are transported from one water molecule to the next over longer distances.
By focusing on explosives hidden in clay soils, the University of Sheffield project – funded by the Engineering and Physical Sciences Research Council (EPSRC) – has addressed a vital gap in knowledge about how buried explosives interact with their surrounding environment. This is a key factor in determining the pattern and extent of the pressure produced by an explosion. Universities and Science Minister Jo Johnson said: "British scientific breakthroughs have saved the lives of millions and we will continue to invest in our scientists as they conduct such game-changing research. The potential for this research to provide better protection for British soldiers and humanitarian workers who risk their lives every day, underscores precisely why we continue to support UK science." The project was part of a wider ongoing initiative – the Defence Science and Technology Laboratory's (Dstl's) programme to understand the effects of IEDs and land mines on armoured vehicles. As well as helping to inform future designs of armoured vehicles, the data produced by the project will aid risk assessment and route planning for operations in current and future combat zones. Dr Sam Clarke, who led the EPSRC-funded project, says: "Detonations of explosives in shallow soils are extremely complex events that involve the interaction of the shock waves with the surrounding soil, air and water. The understanding we've generated about how clay soils affect the process is a key piece in the jigsaw, as it complements the extensive knowledge that's already been built up about explosions in sandy and gravelly soils, which are much less cohesive than clay soils." Using the University of Sheffield's unique Explosives Arena, Dr Clarke and his team carried out around 250 test explosions using different soil samples and made 17 different pressure measurements during each test. The results were backed up and verified by numerical modelling developed and applied as part of an EPSRC CASE (Collaborative Award in Science and Engineering) Studentship. The research has revealed how the blast produced by a landmine or IED would interact, for instance, with anti-mine body armour or an armoured plate fixed underneath a troop transport vehicle. Hundreds of UK service personnel have been killed or injured by IEDs in recent years, while landmines in former warzones worldwide continue to cause thousands of deaths every year. In the face of dangers like these, there is a constant drive to keep improving the capabilities of vehicle armour, personal armour and protective footwear, and this can be aided by a clearer understanding about how explosions actually behave. Dr Clarke comments: "The new data we've generated about the distribution of blast loading in clay soils will feed directly into Dstl's world-class work harnessing the latest science and technology to help protect UK troops and ensure they can operate even more effectively in future."
Using their state-of-the-art simulation facility in the School of Psychology, scientists at The University of Nottingham are exploring use of car driving simulators as tools for training and testing drivers in order to reduce road traffic accidents and fatalities. Each year, over 24,000 people are killed or seriously injured on roads in Great Britain, highlighting the need for more successful techniques to help drivers cope with and avoid hazardous situations. Research led by Hannah Foy, a second year Ph.D. student in Psychology and Cognitive Neuroscience, is looking at whether future interventions could prioritize the use of driving simulators to make us safer at the wheel and our roads a safer place to be. In order to make this possible, it is important to understand if drivers behave comparably in both simulated and real-world driving environments. Hannah’s research has been funded the Defence Science and Technology Laboratory (Dstl). Annalise Whittaker, Behavioural and Cultural Systems Team, Dstl said: “Comparisons of brain activity in real-world versus synthetic environments are important because they allow us to better understand the relationship between synthetic environments and training transfer. This particular piece of research will inform simulator training developments for all military land, air and maritime vehicle operators while also providing useful outcomes for civilian driver safety. Our personnel operate in fast-paced and highly mobile environments where their performance is affected by a number of physical and cognitive burdens, it is vital that their training is fully supported by cutting-edge developments in research.” Limited previous research provides evidence that simulated behaviors do reflect those observed on road. However, Hannah’s research goes above and beyond previous work by investigating the brain activity of drivers using the new driving simulator facility on University Park. Hannah, who graduated with a BSc in Psychology at The University of Nottingham in 2013, said: “Driving simulators provide the opportunity to safely train drivers to deal with hazardous situations that may arise on road but which would be too dangerous to examine otherwise. They, therefore, create the possibility of significant accident reduction through driver testing and training interventions.” Hannah’s Ph.D. “Using near Infrared Spectroscopy to Assess Workload and Inhibitory Control in Real and Simulated Driving Environments” is supervised by Associate Professor Peter Chapman. The research is carried out using the Nottingham Integrated Transport and Environment Simulation (NITES) facility (details of which, along with how to get involved can be found at http://www.lifelongdriving.org). Participants drive a 12-mile loop of Nottingham in an instrumented on-road car; this route is also programmed into a high fidelity motion-based simulator, meaning participants can then drive an identical route in the simulator. Both environments record eye movements and driving behaviors, such as speed. For this research, brain activity is also being recorded using a technique called functional near infrared spectroscopy (fNIRS), which uses light to measure changes in blood concentration in the prefrontal cortex, it is a non-invasive and highly portable technique meaning it can be easily interchanged between car and simulator. After both drives have been completed, the measures are then compared in order to examine the similarities and differences between simulated and on-road driving. Chapman said: “This project showcases the way in which psychological research can be at the cutting edge of both neuroscience and road safety. It will enable us to understand whether behaviors, such as eye movements, brain activity and driving related activities, for instance speed, are the same in a simulator as when driving an identical route in a car.”
News Article | March 24, 2016
A team of scientists, including experts from the UK Ministry of Defence's Porton Down labs, have devised a sensor that can detect even the smallest changes in gravity. The quantum gravity detector can lead to the creation of scanners that can see through walls and detect underground objects. The gravity sensor makes use of lasers to freeze atoms in place, then measures and analyzes how the particles are affected by the gravitational pull and mass of surrounding objects. Using the data derived from the device, scientists can come up with a 3D map that shows the varying densities of objects in the area at which the sensor is directed. The gravity sensor, which was featured on BBC's "Horizon" documentary series on March 23, can also lead to future innovations that are immune to radar detection, jamming or any other sort of interference. Neil Stansfield, of the Defence Science and Technology Laboratory under the Ministry of Defence, explains that the device's resistance to jamming or spoofing is due to its not sending out anything that can be interfered with in the first place. Stansfield adds that until recently, many believed there would be no practical uses for the research. "I think until about five years ago, this was seen as laboratory stuff and it will be 20 or 30 years before we can harness this. My view is that it's much closer," he says. Stansfield remarks that the quantum gravity detector's ability to scan fluctuations in gravity and density gives it the potential to see through objects such as walls. Being able to see underground is an obvious use, he says. "From a national security perspective, the potential is obvious if you can see caves and tunnels,” Stansfield says, adding that the technology can be also be used by civilians. Stansfield notes that half of road development projects are in the wrong place because workers do not know where pipes are buried. The gravity sensor would be able to help workers see exactly where the pipes are underground. The British military's research on controlling gravitational activity has been going on for decades. In the mid-1990s, defense manufacturer BAE Systems began a project that was given the name "Greenglow." The project explored whether elements of science fiction can be turned into reality, such as using antigravity to levitate aircraft and other objects.
In a paper published in Nature Communications, they demonstrate how they synthesised nanometre-sized cage molecules that can be used to transport charge in proton exchange membrane (PEM) applications. Proton-exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for clean and efficient power generation in the twenty-first century. PEMFCs contain proton exchange membrane (PEM), which carries positively-charged protons from the positive electrode of the cell to the negative one. Most PEMs are hydrated and the charge is transferred through networks of water inside the membrane. To design better PEM materials, more needs to be known about how the structure of the membrane enables protons to move easily through it. However, many PEMs are made of amorphous polymers, so it is difficult to study how protons are conducted because the precise structure is not known. Scientists from the University's Department of Chemistry synthesised molecules that enclose an internal cavity, forming a porous organic cage into which other smaller molecules can be loaded, such as water or carbon dioxide. When the cages form solid materials, they can arrange to form channels in which the small 'guest' molecules can travel from one cage to another. The material forms crystals in which the arrangement of cages is very regular. This allowed the researchers to build an unambiguous description of the structure using crystallography, a technique that allows the positions of atoms to be located. The molecules are also soluble in common solvents, which means they could be combined with other materials and fabricated into membranes. They measured the protonic conductivity of these porous organic cages after loading the channels with water, to assess their viability as PEM materials. The cages exhibited proton conductivities of up to 10-3 S cm1, which is comparable to some of the best porous framework materials in the literature. In collaboration with researchers from the University of Edinburgh, Center for Neutron Research at National Institute of Standards and Technology (NIST), and (Defence Science and Technology Laboratory (DSTL), they used a combination of experimental measurements and computer simulations to build a rich picture of how protons are conducted by the cage molecules. Two distinctive features of the proton conduction in organic cage crystals were highlighted as design principles for future PEM materials. First, the cages are arranged so that the channels extend in three dimensions. This means that the movement of the protons is not limited to a particular direction, as in the case of many porous materials tested so far. Second, the cages direct the movement of the water molecules, which means that protons can be passed between them quickly. Also, the cages are flexible enough to allow the water to reorganize, which is also important when protons are transported from one water molecule to the next over longer distances. Dr Ming Liu who led the experimental work, said: "In addition to introducing a new class of proton conductors, this study highlights design principles that might be extended to future materials. "For example, the 'soft confinement' that we observe in these hydrated solids suggests new anhydrous proton conductors where a porous cage host positions and modulates the protonic conductivity of guest molecules other than water. This would facilitate the development of high temperature PEMFCs, as water loss would no longer be a consideration." Liverpool Chemist, Dr Sam Chong, added: "The work also gives fundamental insight into proton diffusion, which is widely important in biology." Dr Chong has recently been appointed as a lecturer in the University's Materials Innovation Factory (MIF). Due to open in 2017, the £68M MIF is set to revolutionise materials chemistry research and development through facilitating the discovery of new materials which have the potential to save energy and natural resources, improve health or transform a variety of manufacturing processes. The paper 'Three-dimensional Protonic Conductivity in Porous Organic Cage Solids' is published in Nature Communications. Explore further: New technique developed to separate complex molecular mixtures More information: Ming Liu et al, Three-dimensional protonic conductivity in porous organic cage solids, Nature Communications (2016). DOI: 10.1038/ncomms12750