The Stanford Synchrotron Radiation Lightsource (SSRL) is one of the pioneering synchrotron facilities in the world, known for outstanding user support, training future generations and important contributions to science and instrumentation. SSRL is an Office of Science User Facility operated for the U.S. Department of Energy by Stanford University.
The world is transitioning away from fossil fuels and hydrogen is poised to be the replacement.
Two things are needed if we are to make the transition to a low carbon, “hydrogen economy” they are clean and high yielding sources of hydrogen, as well as efficient means of producing and storing energy using hydrogen.
Hydrogen powered cars are the perfect case study for how a hydrogen-fuelled future would look. While they work and show a great deal of promise, the best examples of hydrogen being used in fuel require very clean sources of hydrogen. If the source of hydrogen is mixed with contaminants like carbon monoxide, the efficiency of the fuel goes down and causes downstream problems in the fuel cell.
A team from KTH led by Jonas Weissenrieder is visiting MAX IV this week to try and solve this exact problem, how can we generate clean hydrogen for fuel cells? The team is working on a process to catalyse the oxidation of carbon monoxide, which adversely affects fuel cell performance, to harmless carbon dioxide. The catalysis reaction must be selective, and not affect the hydrogen gas that could be oxidised to water which is not great for running car engines.
Work published in the Royal Society of Chemistry with the support of the Helmholtz Association through the Center for Free-Electron Laser Science at DESY, MAX IV Laboratory, Lund University, Sweden, European Research Council (ERC) under the European Union’s Horizon 2020 and the Academy of Finland.
Remember doing titrations in chemistry class? Adding acid drop-by-drop to the beaker and the moment you took your eye off it the solution completely changed colour.
We learned in chemistry that by doing this titration, we were actually affecting an important equilibrium in the beaker between acids and bases. This equilibrium was first described at the turn of the 20th century by American biochemist Lawrence Henderson and modified by Karl Hasselbalch giving us the Henderson-Hasselbalch equation. The discovery and subsequent study of acids and bases using this equation has led to the discovery of many important phenomena in the natural world from as how cells function to how materials are formed.
However, after years of study, an idea arose that questioned the validity of the Henderson-Hasselbalch equation, what happens at the surface? If you have a beaker filled with a dilute acid, what happens at the very top atomic layer? The top layer of a liquid in a beaker is special for many reasons, but if you’re a dissolved molecule, it means that you’re no longer surrounded by water on all sides. For hydrophobic molecules, this means that it is favourable to be at the surface. With this in mind, the scientists took another look at the Henderson-Hasselbalch equilibrium equation and thought that it couldn’t work at the surface. Many studies have measured indicator chemical species, and determined that the Henderson-Hasselbalch equation does not seem to apply at the surface, and concluded that the concentration of hydronium or hydroxide ions, which determines the acidity/basicity, is different at the air-liquid interface than in the bulk.
We are one step further to uncovering a new way to stave off dengue fever thanks to important work carried out at the I02 beamline at Diamond Light Source.
The study, recently published in Nature Immunology, describes how an antibody effectively targets the dengue virus.
Dengue virus affects hundreds of millions of people worldwide and is an untreatable infection. Secondary infections with dengue can lead to a life-threatening form of the disease due to a phenomenon called antibody-dependent enhancement (ADE). Additionally, efforts to develop a vaccine against the virus have been hindered by ADE.
A huge collaborative effort sought to investigate ADE in dengue, and two antibodies were characterised that bound to the envelope protein of the dengue virus. One of the antibodies was found to be a potent neutraliser of the virus, but importantly was unable to promote ADE.
Image: Fab binding in the context of the mature virion. e, Comparison of 2C8 Fab and 3H5 Fab docked onto a E dimer. 2C8 (green) and 3H5 (orange) Fabs were docked onto PDB ID 3J27 by aligning the EDIII potion of the structures. The Fabs are shown as surfaces and the E dimer is displayed in cartoon representation. A side view is of the E dimer on the viral surface is shown. The approximate location of the viral membrane is shown schematically.
For the first time an HZB team was able to examine samples of blue phosphorus at BESSY II and confirm via mapping of their electronic band structure that this is actually this exotic phosphorus modification.
Blue phosphorus is an interesting candidate for new optoelectronic devices. The results have been published in Nano Letters.
The element phosphorus can exist in various allotropes and changes its properties with each new form. So far, red, violet, white and black phosphorus have been known. While some phosphorus compounds are essential for life, white phosphorus is poisonous and inflammable and black phosphorus – on the contrary – particularly robust. Now, another allotrope has been identified: In 2014, a team from Michigan State University, USA, performed model calculations to predict that “blue phosphorus” should be also stable. In this form, the phosphorus atoms arrange in a honeycomb structure similar to graphene, however, not completely flat but regularly “buckled”. Model calculations showed that blue phosphorus is not a narrow gap semiconductor like black phosphorus in the bulk but possesses the properties of a semiconductor with a rather large band gap of 2 electron volts. This large gap, which is seven times larger than in bulk black phosphorus, is important for optoelectronic applications.
Even as our electronic devices become ever more sophisticated and versatile, battery technology remains a stubborn bottleneck, preventing the full realization of promising applications such as electric vehicles and power-grid solar energy storage. Among the limitations of current materials are poor ionic and electron transport qualities. While strategies exist to improve these properties, and hence reduce charging times and enhance storage capacity, they are often expensive, difficult to implement on a large scale, and of only limited effectiveness. An alternative solution is the search for new materials with the desired atomic structures and characteristics. This is the strategy of a group of researchers who, utilizing ultra-bright x-rays from the U.S. Department of Energy’s Advanced Photon Source (APS), identified and characterized two niobium tungsten oxide materials that demonstrate much faster charging rates and power output than conventional lithium electrodes. Their work appeared in the journal Nature.
Currently, the usual approach for wringing extra capacity and performance from lithium-ion batteries involves the creation of electrode materials with nanoscale structures, which reduces the diffusion distances for lithium ions. However, this also tends to increase the practical volume of the material and can introduce unwanted additional chemical reactions. Further, when graphite electrodes are pushed to achieve high charging rates, irregular dendrites of lithium can form and grow, leading to short circuits, overheating, and even fires. Measures to prevent these dendrites generally cause a decrease in energy density. These issues seriously limit the use of graphite electrodes for high-rate applications.
Image: Artist’s impression of rapidly flowing lithium through the niobium tungsten oxide structure. This is a detail of the image, please see here for the entire art work.
Credit: Ella Maru Studio
In-depth investigations on I13 to optimise soft tissue synchrotron X-ray microtomography
The Bradbury Lab at King’s College London, headed by Professor Elizabeth Bradbury, investigates damage to the central nervous system (CNS), and how the body responds to it. The traditional way of investigating soft tissue samples such as those of the central nervous system is 2D histology, in which slices are taken, stained and imaged. However, this process has limitations – slice thickness has a lower limit and measurements within cut slices are subject to inaccuracies arising from mechanical processing distortions. The group sent PhD student (now Dr) Merrick Strotton to the Diamond-Manchester Imaging Branchline I13-2 to investigate whether X-ray microtomography (a nominally non-destructive technique for taking a series of 2D images and turning them into a 3D volume) could avoid these issues. It wasn’t clear how to achieve the best possible results, and so alongside the biomedical studies, Dr Strotton worked with Diamond’s Dr Andrew Bodey on a series of methodological investigations on how to optimise imaging for soft tissue samples, the first results of which have recently been published in Scientific Reports.
Image: Segmentation of the low thoracic-high lumbar (T13-L1) level spinal cord sample from background, white & grey matter from spinal cord and vasculature from spinal cord with SuRVoS.