Tech

Even faster processors with even smaller dimensions? Wherever neither electronics nor spintronics can cope with performance or miniaturization, magnonics comes to the rescue. But before that happens, scientists must learn how to accurately simulate the flow of magnetic waves through magnonic crystals. At the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow an important step in this direction has just been made.

One can argue whether the number of holes in cheese is related to its quality or not. Physicists dealing with magnonic materials do not have such dilemmas: the more holes there are in the material, the more interesting its magnetic properties become, but also radically more difficult to describe and model. In an article published in Scientific Reports a group of experimental and theoretical physicists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow presents a new, experimentally verified model, which for the first time makes it possible to simulate local changes in the magnetic properties of magnonic crystals, with great accuracy. Under this exotic name are hidden thin, multilayered metallic structures containing a regular grid of smaller or larger, more or less contiguous round holes. The Cracow-based analyses also suggest that the magnetic phenomena occurring in magnonic crystals are more complex than previously predicted.

"Multilayer metallic structures with a regular grid of round holes have only recently been studied - and not without problems. The point is that this network of holes dramatically changes the magnetic properties of the system, especially the way in which magnetic waves are propagated in it. The phenomena become so complicated that to date no one has been able to describe or simulate them well", says Dr. Michal Krupinski (IFJ PAN).

Electronics is the processing of information by means of electric charges of electrons flowing through the system. Spintronics, tipped to be the successor of electronics, also uses streams of electrons, but pays attention not to their electric charge, but to spin (in other words: to the magnetic properties). Against the background of both these fields, magnonics distinguishes itself fundamentally. There are no organized flows of media in magnonic devices. What flows through the system are magnetic waves.

The differences between these areas are more easily understood by an analogy with the world of sport. When a stadium fills or empties, streams of people flow within it. If electronics worked here, it would pay attention to the numbers of people entering and leaving the stadium. Spintronics would also observe the movement of people, but it would be interested in the movements of people with light or dark hair. In this analogy, magnonics would deal with the flow... of Mexican waves. Waves like this can circle the entire stadium despite the fact that no one fan moves away from his seat.

The physicists from Cracow produced their magnonic crystals using the method invented by Prof. Michael Giersig from Freie Universität Berlin and developed in IFJ PAN by Dr. Krupinski. The first step is to apply polystyrene nanoparticles onto a non-magnetic substrate (e.g. silicon). The spheres are self-organising and can do this in different ways depending on the conditions. The substrate covered with organised spheres is then subjected to the action of plasma in a vacuum chamber, which allows the diameter of the spheres to be reduced in a controlled way. Thin layers of suitable metals are then applied to the sample thus prepared, one after another. After all the layers have been applied, the material is washed with organic solvents to remove the spheres. The end result is a periodic structure resembling a more or less dense sieve, permanently bonded to a silicon substrate (potentially it does not need to be rigid, the team from the IFJ PAN can also form similar structures e.g. on flexible polymer substrates).

"The systems we studied consisted of 20 alternating layers of cobalt and palladium. These are very thin structures. Their thickness is only 12 nanometres, which corresponds to about 120 atoms", says Dr. Krupinski.

Depending on the size of the holes, larger or smaller areas with shapes similar to a triangle are formed between their points of contact. Atoms within these areas can be magnetised in the same way forming so-called magnetic bubbles. These bubbles can be used to store information, and changes in their magnetization allow for the propagation of magnetic waves in the system.

The theoretical model, built in IFJ PAN under the direction of Dr. Pawel Sobieszczyk, describes magnetic phenomena occurring in crystals with dimensions of two by two micrometres. On the scale of the microworld, these dimensions are huge: the number of atoms is so large that it is no longer possible to simulate the behaviour of single atoms. However, due to the mutual magnetic interaction, the magnetic moments of adjacent atoms are usually oriented in almost the same direction. This observation allowed atoms to be grouped into small volumes (voxels), which could be treated as single objects. This procedure radically reduced the computational complexity of the model and made it possible to carry out numerical simulations, which were performed at the Academic Computer Centre Cyfronet AGH University of Science and Technology in Cracow.

"The key to success was the idea of incorporating imperfections found in real magnonic crystals into the model", says Dr. Sobieszczyk and enumerates: "First of all, real structures are never perfect crystals. They are usually clusters of many crystals called crystallites. Depending on the size and shape, crystallites can have different magnetic properties. Moreover, chemical contaminants may appear in the system. They cause certain areas of the material to lose their magnetic properties. Finally, the individual metallic layers can be thicker or thinner in places. Our model works so precisely because it takes all these effects into account".

The model presented here predicts the existence of an interesting, hitherto unobserved phenomenon. When two adjacent bubbles are magnetised reversely, the magnetic moments of the atoms between them can change their orientation either by rotating parallel to the plane of the layer or perpendicularly. A kind of wall is then created between the bubbles, in the first case called a Bloch wall, in the second - a Néel wall. Until now, it was assumed that only walls of one kind could be found in a given magnonic crystal. The model developed by physicists from the IFJ PAN suggests that both types of magnetic walls can occur in the same crystal.

Magnonics is only just getting started. The path to complex processors - smaller, faster, and with a logical structure that could be reprogrammed according to needs - is still a long way off. Magnonic memories and innovative sensors capable of detecting small amounts of substances seem more realistic. Understanding the mechanisms responsible for the magnetic properties of magnonic crystals and the ways magnetic waves flow brings us closer to these types of devices. This is an important step, after which the next ones will surely come.

The Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN) is currently the largest research institute of the Polish Academy of Sciences. The broad range of studies and activities of IFJ PAN includes basic and applied research, ranging from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of methods of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly yield of the IFJ PAN encompasses more than 600 scientific papers in the Journal Citation Reports published by the Thomson Reuters. The part of the Institute is the Cyclotron Centre Bronowice (CCB) which is an infrastructure, unique in Central Europe, to serve as a clinical and research centre in the area of medical and nuclear physics. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: "Matter-Energy-Future" which possesses the status of a Leading National Research Centre (KNOW) in physics for the years 2012-2017. The Institute is of A+ Category (leading level in Poland) in the field of sciences and engineering.

Overweight and obesity have become a severe public health problem around the world. Current anti-obesity strategies are mainly aimed at restricting calorie intake and absorption. Now, Chinese scientists suggest in a new study that burning energy by activation of brown adipose tissue (BAT) might be an alternative strategy for combating obesity.

The researchers found that an extract from ginseng, a Traditional Chinese Medicine (TCM) herb, can induce Enterococcus faecalis, which can produce an unsaturated long-chain fatty acid (LCFA) - myristoleic acid (MA).

"As a novel anti-obesity probiotic, E. faecalis and MA can reduce adiposity via BAT activation and beige fat formation," said JIN Wanzhu, lead author of the study and a scientist at the Institute of Zoology of the Chinese Academy of sciences.

Previous studies have shown that BAT facilitates weight control and generates a potent anti-obesity effect. Therefore, increasing BAT activity could be a novel and effective therapeutic approach for obesity and its related diseases, said JIN.

This is the first proof that the E. faecalis LCFA (specifically MA) axis can reduce obesity by increasing BAT activity and beige fat formation.

"This study demonstrates the important role of MA in reducing obesity and improving related metabolic syndrome, as well as its tremendous application prospects," said JIN.

A research team in Trinity College Dublin has uncovered a critical role for a protein called 'PKM2' in the regulation of immune cell types at the heart of multiple inflammatory diseases.

The work identifies PKM2 as a potential therapeutic target for treating a host of diseases mediated by over-active immune cells, such as psoriasis and multiple sclerosis. The findings are reported today in the world's leading metabolism journal Cell Metabolism - with the chief discovery being that PKM2 is a central 'on' switch for these cells.

Lead author Stefano Angiari, working with a team led by Luke O'Neill, Professor of Biochemistry in the School of Biochemistry and Immunology in the Trinity Biomedical Sciences Institute, has been exploring the role of PKM2 in the regulation of two cell types called 'Th17' and 'Th1' cells.

Dr Stefano Angiari, Trinity, said:

"Th17 and Th1 cells are very important for the damage that happens in autoimmune diseases such as psoriasis and multiple sclerosis. We have found that interfering with PKM2 blocks these cells and limits inflammation."

Professor Luke O'Neill added:

"PKM2 is a fascinating protein that has a role in how cells use glucose for energy, but it also moonlights in the immune system, where we have found it can be especially troublesome. We are currently exploring it as a new target for therapies that might work in patients with diseases like psoriasis and multiple sclerosis, where treatment options are limited."

The study was funded by the EU Marie Curie programme (which funded Dr Angiari), and the Wellcome Trust.

Wolfe Creek Crater, one of the world's largest meteorite craters, is much younger than previously thought.

Wolfe Creek Crater is situated on the edge of the Great Sandy Desert in northern Western Australia. It is the second largest crater on Earth from which meteorite fragments have been recovered (the largest is Meteor Crater in Arizona).

It was likely formed by a meteor about 15 metres in diameter, weighing around 14,000 tonnes.

The age of the impact is poorly understood and unpublished data suggests the impact could have occurred around 300,000 years ago.

However, according to a new study led by Dr Tim Barrows from the University of Portsmouth, the most likely age for the impact is 120,000 years ago.

In the study, published in the journal Meteoritics & Planetary Science, researchers from the University of Portsmouth, Australia and the USA calculated the new age of Wolfe Creek Crater using two geochronological dating techniques.

First, the researchers collected samples from around the crater rim and applied exposure dating, which estimates the length of time that a rock has been exposed at the Earth's surface to cosmic radiation.

They were also able to determine the age through optically stimulated luminescence, (a dating technique used to measure how long ago sediment was last exposed to sunlight) on sand buried after the impact.

Dr Barrows said: "The crater is located in a fortuitous situation where we can use two different techniques to determine its age. The impact of the meteorite tilted and overturned the rock, exposing rock that was previously shielded from cosmic radiation. The newly formed crater also deflected the local wind field and created a new set of sand dunes. Results from the two dating techniques mutually support each other within the same age range."

The researchers were able to produce a new topographic survey of the crater using aerial photos by Ted Brattstrom, a school teacher from Hawaii. He flew over the crater in a light aircraft in 2007 and took pictures of the crater from all directions.

The resulting 3D model was used to create a digital elevation model of the crater. The researchers calculate that the maximum width of the crater is 946 metres in a NE-SW direction, reflecting the direction of the impact. The average diameter is 892 metres.

They also predict a crater depth of 178 metres and that it is filled by about 120 metres of sediment, mostly sand blown in from the desert.

Wolfe Creek Crater is one of seven sets of impact craters in Australia dating to within the last 120,000 years. From this, the researchers were able to calculate as to how often these crater-producing events occur.

Dr Barrows said: "Although the rate is only one large meteor hitting Australia every 17,000 years, it isn't that simple. The craters are only found in the arid parts of Australia.

"Elsewhere, the craters are destroyed by geomorphic activity like river migration or slope processes in the mountains. Since Australia has an excellent preservation record with dated craters within the arid zone, we can estimate a rate for the whole Earth. Taking into account that arid Australia is only about one per cent of the surface, the rate increases to one hitting the Earth every 180 years or so. There have been two big objects hitting the atmosphere in the last century - Tunguska in 1908 and Chelyabinsk in 2013.

"This is a minimum estimate because some smaller impacts were probably covered by sand during the last ice age. The number of large objects the atmosphere is probably 20 times this number because stony meteorites are far more common but not as many survive the fiery journey through the atmosphere or effectively make craters. Our results give us a better idea of how frequent these events are."

Using the same geochronological dating techniques, the researchers were also able to recalculate the age Meteor Crater. They found it is likely to be 61,000 years old, over 10,000 years older than previously thought.

Given the anthropological and climate threats facing nature, the conservation of tropical biodiversity is a major challenge. To encourage the implementation of better biodiversity management practices, countries and international agreements on biodiversity refer to the assessments of species "at risk of extinction" performed by the IUCN as part of a standardised procedure (See Red List of Threatened Species). This approach remains the most comprehensive and objective means of identifying species in need of protection.

However, while the conservation status of the majority of vertebrate species has been assessed, the same cannot be said for plants, although they are critical to earth ecosystems. This is especially true in tropical regions where the flora is very diverse but remains poorly documented.

6,990 Potentially Threatened Species

In this study, the researchers developed a new fast and automatic approach based on key elements of the conservation assessment process used by the IUCN. Their objective was to provide relevant information on the conservation status of a large number of plant species at broad scales, in the form of Preliminary Automated Conservation Assessments (PACA).

The researchers therefore applied this methodology to the RAINBIO database, which contains over 600,000 georeferenced occurrences of plants in tropical Africa across more than 20,000 vascular plant species.

After classifying these species into six categories - which include species that are "probably or potentially threatened", those that are "potentially rare" and those that are "potentially not threatened" - they reveal that almost a third (31.7%) of the 22,036 vascular plant species studied are potentially threatened with extinction, and an additional 33.2% are potentially rare (they could be threatened in the near future).

Facilitating Large-Scale Biodiversity Assessments

After determining the most endangered species, the researchers identified four regions in Africa that are particularly exposed: Ethiopia, central Tanzania, the south of the Democratic Republic of the Congo and the West African tropical rainforests.

They highlight the advantages of this approach, based on the preliminary automated conservation assessments, in terms of cost reduction, time saving and the potential to carry out large-scale assessments. "This study is the first large-scale assessment of the potential conservation status of the tropical African flora, explicitly using the IUCN's methodology", explains botanist Thomas Couvreur from the IRD who coordinated the study. "These assessments could provide crucial information for improving biodiversity management and promoting sustainable economic development in Africa. They are, however, not intended to replace the comprehensive assessments carried out by the IUCN which lead to official statuses. The two approaches are complementary, and a significant international effort is still needed to assess all plant species in Africa", he urges.

"These results were possible because the partners involved agreed to share their data", says Bonaventure Sonké, Professor at the Laboratory of Systematic Botany and Ecology of the Ecole Normale Supérieure (University Yaounde 1, Cameroon). "This is a strong signal to encourage researchers to share their data, in order to obtain results on a larger scale".

In a paper to be published in the forthcoming issue in NANO, a group of researchers from the Shenyang Jianzhu University in China provide an overview of single molecule electronic devices, including molecular electronic devices and electrode types. Future challenges to the development of electronic devices based on single molecules are described, in the hopes of attracting more experts from different fields to participate in this research.

How small can computers be in the future? Can you imagine how molecular machines works?

At present, traditional electronic devices based on semiconductor materials will face severe challenges. These challenges are not only technical and technological limitations, but also, more importantly, theoretical limitations. With the rapid development of nanotechnology and in-depth research, great progress has been made in the theory and practice of molecular electronic devices in recent years

Molecular electronic devices are devices that use molecules (including biomolecules) with certain structures and functions to build an ordered system in the molecular scale or supramolecular scale. They make use of the quantum effect of electrons to work, control the behavior of single electrons, and realize the functions of information detection, processing, transmission and storage, such as molecular diodes, molecular memories, molecular wires, molecular field effect transistors and molecular switches.

As a stable quantum system with abundant photoelectric properties, molecules have many electronic transport properties different from semiconductor devices. Molecular electronic devices have the following advantages: (1) small molecular volume, which can improve the integration and operation speed; (2) selecting appropriate components and structures can widely change the electrical properties of molecules; (3) molecules are easy to synthesize, and the required structure can be formed by a self-assembly method; and (4) the molecular scale is on the nanometer scale and has advantages in cost, efficiency, and power consumption.

With the traditional silicon-based electronic devices becoming smaller and smaller, the impact of quantum effect is gradually recognized. The research on molecular electronics has made significant breakthroughs. As more and more excellent characteristics such as potential thermoelectric effects, new thermally induced spin transport phenomena and negative differential resistance are discovered and understood, it is believed that "smaller", "faster" and "cooler" high-tech products will eventually be realized in the future.

However, current research work on molecular devices is still theoretical, and there is still much work to be done in terms of device manufacturing reliability, experimental repeatability, and manufacturing cost. Therefore, the purpose of this review is to attract more experts, scholars and engineers from different fields such as chemistry, physics and microelectronics to participate in this research, so that molecular electronic devices can become a reality as soon as possible.

CHAMPAIGN, Ill. -- From mid-November 2015 through February 2016, scientists used GPS transmitters to track the movements of Canada geese near Midway International Airport in Chicago. They discovered that - in the colder months, at least - some geese are hanging out on rooftops, in a rail yard and in a canal close to Midway's runways. This behavior increases the danger of collisions between geese and airplanes, the researchers say.

The study is reported in the journal Human-Wildlife Interactions.

The Federal Aviation Administration recommends that - depending on the type of aircraft served - airports maintain a 5,000- to 10,000-foot buffer around runways that is free from wildlife attractants. But the study revealed that the geese are using man-made structures inside the buffer zone at Midway Airport.

The researchers placed neck-collar-mounted GPS transmitters on 31 geese captured in parks from within a 7.5-mile zone around Midway Airport. The team collected hourly data on each bird's altitude and position over four months.

Study lead author Ryan Askren, a graduate student at the University of Illinois, said it was important to follow the birds' precise movements from site to site.

"We knew there were lots of geese around the airport, and we had an idea of what habitats they were using," he said. But knowing how the birds moved - and at what altitude while in proximity to runways - was critical to understanding the risk to airplanes.

"What we didn't understand before we started looking into it is that the geese are acting very oddly," said Michael P. Ward, a U. of I. professor of natural resources and environmental sciences and Illinois Natural History Survey avian ecologist who led the research. "Their behavior is different than what most wildlife biologists would think of as typical for geese."

Early in this study, co-author Brett Dorak, a graduate student in Ward's lab at the time, used transmitters to track Canada geese using rooftops and rail yards in the vicinity of the airport. He found that some of the geese visited those sites quite often. Flight paths of the geese traveling between these locales and parks and other open spaces nearby showed that the geese were often crossing the runway approaches.

"Of the 3,008 goose movements we recorded, 821 came within 10,000 feet of airport runways," Askren said. "Of those, 399 intersected the flight paths of approaching and landing aircraft."

"I think the geese are on the rooftops because they don't want to be disturbed," Ward said. "No one's jogging past them, no cars are honking at them. They can sit up there and conserve energy and not move. I think their whole behavior is to conserve energy, since there isn't much for them to eat in Chicago in the winter."

The canal doesn't freeze and is a bit warmer than other open water, so it offers another opportunity for the geese to avoid expending too much energy, Ward said.

What little sustenance is available to them might be found in the rail yard, the researchers said. Photos taken by Dorak revealed what look like piles of moldy grain in one section of the rail yard.

"They won't let us in there, but it looks like these rail cars haul grain and then they don't get all of the grain out," Ward said. "They take the rail cars to one end of the yard and somebody brushes them all out and it makes these mountains of moldy grain."

Some of the study geese regularly visited the rail yard and were likely eating the grain, Ward said.

"These geese are using clever behaviors to find whatever resources they can get," he said. "It just doesn't make sense physiologically that they are going to make it through the winter eating dead grass, and so they've got to be creative."

While the study focused on geese near Midway Airport, Ward said he thinks the findings are broadly relevant.

"The behavior of the geese at Chicago is going to be similar to the geese around airports in Toronto, Minneapolis, Madison or Des Moines - any airport in the upper temperate region," he said. "Wherever you go, these geese are adapting to humans and changing their behaviors to take advantage of any opportunities they have."

The researchers suggest that owners of buildings near the airport set up devices to dissuade geese from using rooftops. They hope that rail yard managers will find another way to dispose of grain, and that those managing lands near the canal will find ways to scare off the geese.

"Make it so it's not a hospitable place for the geese," Ward said. "I realize the geese will probably cause a problem somewhere else, but they won't be causing a problem for airplanes."

Researchers at the Niels Bohr Institute, University of Copenhagen and DTU Space in Lyngby have determined the emission of extremely energetic light particles during the death of a very heavy star for the first time. The discovery was made in collaboration with a large, international team of scientists. The light particles were measured with the telescope MAGIC, situated on the Canary Islands. The researchers at the Niels Bohr Institute subsequently measured the particles with the neighboring Nordic Optical Telescope. The scientific perspective - the source detection of the emission of particles - is to gain basic insights into the extreme physical processes in the death of the heaviest stars. The study is now published in the journal Nature.

Gamma Ray Burst - what is that?

When a heavy star dies or collapses, it happens in the form of a supernova - a gigantic explosion. In about a ten thousandth of the supernovae it is even more violent. "Presumably a black hole or an extremely magnetic neutron star is formed", Johan Fynbo from the Cosmic DAWN Center at the Niels Bohr Institute explains. The matter is compressed to form an enormously compact object, spinning extremely fast. The magnetic field along the rotational axis can become intense and emit energetic particles in the direction of the axis in what the researchers names as a "jet". If it points in our direction, we see a gamma ray burst.

Extremely energetic particles in the gamma ray burst reach us on Earth.

The particles (electrons) emitted in the jet, strike light (photons) in their path and transfer the energy to the photons. The photons travel through the Universe, eventually to be detected and measured on Earth. Johan Fynbo and his colleagues, Daniele Malesani, Jonatan Selsing, Kasper Heintz and Luca Izzo observed the gamma ray burst only 29 minutes after its arrival on Earth and succeeded in measuring the distance to it. The distance is crucial in order to identify the source, which you have to know to understand the processes emitting a gamma ray burst this energetic into space. "It is extremely relativistic, which means that the jet emitted from the gamma ray burst travels with 99.999% of the speed of light, the fastest possible speed. And the basic understanding of the most extreme processes in space are at the center of the subsequent research. The discovery of a gamma ray burst also shows us that on this position in the Universe, the conditions for this extreme situation exist. In other words, we can use the gamma ray burst to learn more about these conditions as well", Daniele Malesani explains.

The Sun is born - and an old star dies

The distance is important for a number of reasons: The intensity of any radiation, including the light from the gamma ray burst, fades with the distance it travels, so the energy-calculation of its source tells us it must have been a very energy packed event indeed. When we know the distance, we can calculate the time of the explosion as well: It took place 4.5 billion years ago. When we look into space, we also look back in time. The supernova happened almost simultaneously with the forming of our own sun. Since then, the light from the gamma ray burst has travelled through space and reached Earth on 14th of January 2019. The gamma ray burst is in the constellation "Fornax".

International collaboration - and an important upgrade of The Nordic Optical Telescope

The scientific article is the result of a collaboration between many researchers from all over the world, and the important distance measurement and positioning of the gamma ray burst were made by the team at the Niels Bohr Institute. This particular task it is expected to be solved with more ease at the Niels Bohr Institute in the future, thanks to a grant from the Carlsberg Foundation for a scientific instrument added to the Nordic Optical Telescope. "Within 5 years, we should become much better at following up on this type of transients or violent, short lived, astrophysical events with The Nordic Optical Telescope. Several research projects are under way, and they should enable us to discover many more of the energetic light particles from dying stars and other extreme objects, in order to be able to study this type of physics in much better detail", Johan Fynbo explains.

Dutch artist M.C. Escher's most famous drawing, "Circle Limit IV (Heaven and Hell)", shows angels and demons in a tessellation that fills a circle without empty spaces. This masterful woodcut inspired an international partnership of researchers including Politecnico di Milano Physics Department to author the cover-story article published in Physical Review Letters (*).

This free and unconventional work-of-art has provided a valuable assistance to science.

The discovery

The researchers of Professor Paolo Biscari's group, together with their colleagues discovered that the arrangement of angels and demons in the famous woodcut makes it possible to predict how a crystalline body will change its shape when subject to external action.

Escher's woodcut is linked to the work of mathematicians who in the middle of the last century were exploring the properties of hyperbolic spaces:

The study's subject showed a connection between these spaces and everyday phenomena such as the permanent plastic deformation of matter.

The work-of-art sparked a new approach to the mathematical description of complex material deformation phenomena problem.

The new approach mooted by the researchers indicates how crystalline lattice shapes can be associated with points in the hyperbolic space. During its deformations, the material changes shape, passing e.g. from one Escher's angelic image to the next angel's shape.

Crystal plasticity is due to the interactions of lattice defects that glide under the effect of the applied forces.

The model promises to become a new useful tool for the study and numerical simulation of microscopic plastic phenomena. Conventional theories cannot correctly describe many properties such as mechanical strength and its unpredictable fluctuations, which can generate true plastic avalanches.

Controlling these phenomena opens new paths for the design and development (guided by theory and simulation) of new materials to optimise micro-manufacturing processes.

A high percentage of schools buildings in Andalusia does not have the necessary mechanical ventilation equipment or filtration systems in place, so air has to be renewed by means of infiltrations or opening the windows. A recent University of Seville study has analysed the air tightness of classrooms in Andalusia and the evolution of CO2 levels during the school day, via in situ monitoring, which serves as an indicator to determine air quality.

To that end, different tests were carried out in 42 classrooms in 8 education centres, spread across the different climatic zones that are typical of Andalusia, and in two different time periods, winter and autumn/spring, in which pressurisation and depressurisation tests were carried out to obtain the n50 value (the estimated rate of air renewal per hour for a space with a internal and external pressure difference of 50 Pascals). In addition, air temperature, relative humidity and Co2concentration were recorded, in order to study the impact of opening the windows by different degrees. At the same time, 917 students (between the ages of 11 and 17) were questioned about possible symptoms and health effects.

As a result of the research, he average values of air renewal obtained with windows and doors closed were approximately 7 h?1 (average air tightness), while the average values for CO2 concentration was about 1900 ppm, with only 17% of the total case studies showing values less than the 1000 ppm recommended for healthy environments by the WHO. Also, it was concluded that 42% of the case studies showed concentrations higher than 2000 ppm with the windows closed. In addition, it was shown that there was a higher level of symptomology, or level of discomfort as perceived by the students, when the windows were open (33% of the case studies). In contrast, certain symptoms, such as itchy skin and nasal congestion, could be identified as occurring in the periods in which the windows were closed, as these appear when CO2 levels are higher.

"Both the symptoms and the elevated levels of CO2 found show the possible degradation of air quality in the classrooms of Andalusia", states the University of Seville researcher Miguel Ángel Campano, who adds, "It is necessary to install controlled mechanical ventilation systems, so that they meet the current new-building regulations as well as the environmental ergonomic norms developed in Europe. It seems opportune to have the ability to filter external contaminants and to be able to guarantee the minimum external renewal airflow, to achieve CO2 concentrations below 1000 ppm".

In the published study, data is collected from 8 different schools, of which 25% are from before 2008, the year in which the Regulation of Thermal Installations in Buildings (Reglamento de Instalaciones Térmicas de los Edificios - RITE 2007) came into force, which means they do not have to meet this regulation's requirements. Of the other 75% of centres, only one has the necessary mechanical ventilation equipment to comply with this regulation, although during the period of the tests, it was established that these "had never taken effect" (according to the information gathered).

Redox flow batteries are an emerging technology for electrochemical energy storage that could help enhance the use of power produced by renewable energy resources. These power resources are inherently irregular in their supply, which doesn't typically align with demand on the power grid. In principle, redox flow batteries can be designed to have an energy-storage capacity that is independent of its power rating. However, in practice, the ease with which redox-active molecules are transported to electrode surfaces plays an important role in determining their efficiency, the power that is produced or charged and, in some instances, their length of life.

In a new paper, Assistant Professor Kyle Smith addressed these challenges with a new theory to predict how fluid flow affects the ability of molecules in a flow battery to react at the surfaces of porous electrodes. "Modeling the Transient Effects of Pore-Scale Convection and Redox Reactions in the Pseudo-Steady Limit" was published in a focus issue of the Journal of the Electrochemical Society in honor of Illinois' Richard C. Alkire, the Charles J. and Dorothy G. Prizer Chair Emeritus in the Department of Chemical and Biomolecular Engineering, former Vice Chancellor for Research, and former Dean of the Graduate College. Alkire is known world-wide for his expertise in metal deposition and multi-scale simulations from atomic-to-processing scales.

Smith and his PhD student theorized in the research that the rates of reaction at microscopic scales were relevant to the underlying microscopic structure of the electrode material. The results of his model enabled him to predict how molecular transport occurs under so-called transient conditions, where the concentrations of redox-active molecules in the battery's electrolyte change with time.

"We showed that these conditions are particularly relevant to the operation of redox flow batteries, which experience dynamic charge and discharge processes in which electrolyte composition changes with time. This was in contrast to earlier work that had considered such effects primarily from a steady state context where composition is constant in time," said Smith. "The theory we introduced enables the prediction of mass transfer coefficients based on the microscopic pore structure within electrodes that electrolytes are charged and discharged within. Having such capabilities enables us to engineer how such structures should be designed--in other words, how to engineer them."

Smith's finding impacts numerous engineering applications where pore-scale transport is important, including water purification and desalination, catalytic purification of industrial and vehicle exhaust, and transport of reactive minerals and biodegradation of living cells.

This work relates well to Alkire's career research in improving design in engineering through multi-scale simulations. "The overarching goal of this special volume is to address the need for new engineering methods, driven by remarkable discoveries at the scale of molecules, as well as rapid growth in massive data archives. The focus is on developing new design methods for linking behavior at the molecular scale with traditional electrochemical engineering design procedures at the macroscopic scale. The purpose is to embed quality control at the molecular scale into well-engineered products and processes," said Alkire of the focus issue published in his honor.

From a modest 150 words to the length of a children's book - the number of words used by politicians in their election manifestos has grown substantially in the past century, new research shows.

Far from becoming irrelevant because few voters now manage to plough through the mammoth documents, manifestos now have a quasi-constitutional significance, according to historians.

Although manifestos have no formal status in law, they now have a symbolic value as embodying the will of the people, used if necessary to overcome any objections from civil servants or the House of Lords, according to the University of Exeter study.

Professor Richard Toye and Professor David Thackeray have calculated that between 1900 and 1997 the Conservative party used 197,898 words in total in their manifestos, Liberal or Liberal Democrat 127,803 and Labour 142,526.

In 1900 the Conservative manifesto was 880 words long, the Liberal manifesto 1,790 and Labour 150 words. The size gradually grew, and by 1970 the Conservative manifesto was 10,676 words long, Liberal 2,871 and Labour 11,735. By 1997 the Conservative manifesto was 21,053 words long, Liberal Democrat 14,007 and Labour 17,657.

The main part of the 2019 Labour manifesto is 26,175 words long, while the Liberal Democrat manifesto has 28,146 words.

Between 1900 and 1997 manifestos were longest in 1992, with all three parties using a total of 53,259 words, compared to 1910, when parties used just 1,076 words in total in their manifestos.

The analysis, published in the journal Twentieth Century British History, shows all three parties have struggled to be comprehensive, but also ensure their manifesto acts as punchy propaganda. In 1983, Labour's internal crisis meant that it was "unable to prepare a short, popular and lively manifesto" and instead fell back on a previously prepared 22,000 word 'Campaign Document', famously described as being "the longest suicide note in history". Yet politicians could produce shorter manifestos if they wanted, as shown by some of the manifestos of the 1950s, and by Labour's successful efforts in 1987 and 1992 to avoid another overlong document.

Professor Thackeray said: "After 1945 central party staff increasingly dominated election campaigns. Most candidates waited until the party manifesto had been released before finalising their own election address, this meant they were less likely to issue pledges which might clash with the national programme. This meant by the end of the century MPs were chiefly considered representatives of a party with a formal mandate to carry out manifesto pledges."

Labour has used detailed pledges in its manifestos from the 1920s onwards to challenge antisocialist scaremongering and present itself as a credible party of government. After 1950 the Conservative Party used the same tactic, of making their manifestos more specific, to win over cynical voters.

Margaret Thatcher sought to tap into public disillusionment with state intervention, organising Conservative election manifestos around a few, detailed pledges. The later New Labour approach drew on Thatcher's practice, in order to forestall the classic Conservative claim that the party's plans were unaffordable. The Conservatives were the first party to use civil servants to 'cost' an opposition manifesto in 1964.

Professor Toye said: "Although few voters read manifestos from cover to cover, they are still important symbolic part of the electoral process. But in view of their ballooning length many people will ask themselves if politicians, having abandoned the search for the magic money tree, have instead located a magic typewriter."

The local release of antitumoral drugs through bacterial proteins in the treatment of breast cancer can mark a before and after in precision medicine. In this sense, researchers at the CIBER of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) of the Universitat Autònoma de Barcelona (UAB), the Vall d'Hebron Research Institute (VHIR) and the Spanish National Research Council (CSIC) have created Escherichia coli cell structures to produce non-toxic bacterial amyloids.

Inclusion bodies or amyloids are nanostructured protein aggregates produced inside a cell, frequently found in specific bacteria and with interesting biomedical applications such as protein drug release, as is the case here.

These protein structures act as antitumoral drug secretion granules and since they are administered locally, they have a sustained therapeutic effect throughout time. Although this research, published in Advanced Science, is still in the first stages of development, the cross-cutting principle described in the study opens a broad experimentation field for the generation of new therapeutic biomaterials produced within bacteria for precision medicine aimed at breast cancer and other high incidence neoplasms.

This research project, funded by the TV3 Marathon Foundation, was coordinated by the UAB's CIBER-BBN researcher Esther Vázquez, and also included the participation of Ibane Abasolo (Vall d'Hebron Hospital) and Miriam Royo (CSIC). The consortium also included the collaboration of Laura Soucek from the Vall d'Hebron Cancer Research Institute (VHIO) and ICREA, and expert in animal models for the study of cancer.

According to Esther Vázquez, "although this technology still has a long way to go before being applied clinically, the results obtained in this study, which has lasted over three years, pave the way for a new therapeutic technology based on bacterial products which have not been clinically explored yet".

The study is based on a directed release of CD44+ tumour cells in animal models of human breast cancer, of two antitumoral proteins (Omomyc and p31) in the form of nanostructured materials. The main novelty of the study lies in the use of toxic-free bacterial amyloids as a reservoir for these therapeutic proteins. The local administration of this material fosters a sustained release of the drugs and the necrosis of tumour tissue in a relatively short period of time. One of the main advantages of using these types of materials is a sustained protein drug release, which lowers the frequency of administration in relation to the current standards for conventional drugs.

The quest to develop the understanding for time crystalline behaviour in quantum systems has taken a new, exciting twist.

Physics experts from the Universities of Exeter, Iceland, and ITMO University in St. Petersburg, have revealed that the existence of genuine time crystals for closed quantum systems is possible.

Different from other studies which to date considered non-equilibrium open quantum systems, where the presence of drive induces time-periodic oscillations, researchers have theoretically found a quantum system where time correlations survive for an infinitely long time.

Published in Physical Review Letters as Editors' Suggestion on November 20th, the study could pave the way to the development of novel, exciting applications, such as a new kind of atomic clocks.

The notion of a time crystal (TC) was first put forward by the esteemed physics Nobel laureate Frank Wilczek in 2012. The central role in establishing time crystal as a new phase of matter corresponds to breaking of the time translational symmetry.

In everyday life we are surrounded by solids, where atoms and molecules form a periodic structure along the spatial coordinates.

Unlike ordinary crystals - such as diamonds - with properties defined by atoms being regularly arranged in space, time crystals instead show an ever-changing mode of behaviour that repeats in time.

However, the very possibility of time-translational symmetry breaking turned out to be notoriously difficult in a perfectly isolated quantum system which remains in equilibrium. Notably, the theorem proven by Haruki Watanabe and Masaki Oshikawa stated that quantum version of time crystals are impossible, unless: 1) highly non-local interactions are present in a genuine quantum system; or 2) a driven system is considered.

In particular, using the second loophole, scientists have shown in recent years that different time crystals variants (most notably discrete or Floquet time crystals) are possible to produce.

The question: "Can the original concept of time crystal be realised?" thus remained in the air.

In the new study, the research team led by Oleksandr Kyriienko from the University of Exeter has shown that it is possible to 'bypass' the no-go theorem for the existence of quantum time crystals, and that the genuine time crystalline order is indeed possible.

The key ingredient corresponds to finding the Hamiltonian - an operator which describes the energy of a quantum system - which fully satisfies the conditions for TC behaviour posed by Watanabe and Oshikawa.

The team has found that the system which breaks the time-translational symmetry necessarily possesses multiparticle interactions (so called "strings") where at least half of particles interact simultaneously.

The associated ground state correlation function exhibits perpetual oscillations due to coupling between two maximally entangled states corresponding to Schrodinger cat-like states.

The findings could help further scientist's understanding of how condensed states of matter behave, and shed the light on physics of dynamical orders.

Being the first step towards breaking the continuous time-translational symmetry, the study attracts attention to other possible quantum systems where long-range interactions may induce non-trivial dynamics.

Oleksandr Kyriienko said: "Now we know that time translational symmetry can be broken with highly nonlocal interactions. Can we improve on that and have practically useful systems with reduced interactions where correlations survive at infinite times? I don't know for sure, but am eager to find out."

A tide of public momentum is swelling against the crisis of petroleum-based plastics, which are sitting in our landfills, floating in our oceans, and showing up in our air and even our food.

Meanwhile, in a Colorado State University chemistry laboratory, polymer scientists are toiling toward what they think is a viable solution. Every day, they are working on new chemistry for sustainable materials that could compete with, and eventually even replace, the hard-to-recycle, non-degradable commodity plastics that have overwhelmed our environment for decades.

Eugene Chen, professor in the Department of Chemistry, has led a new study demonstrating a chemical catalysis path for making an existing class of biomaterials - already gaining momentum in industrial settings - even more commercially viable and structurally diverse. The results are published in the journal Science, and the paper includes first author Xiaoyan Tang and graduate student co-authors Andrea Westlie and Eli Watson.

In recent years, Chen has focused some of his lab's efforts on a set of biomaterials called PHAs, or polyhydroxyalkanoates. They're a class of polyesters, produced by bacteria, that are biodegradable to a degree not seen in commercial plastics. They beat out "compostable" bioplastics made out of polylactic acid (PLA) by degrading naturally in oceans and landfills, whereas PLA needs to be composted industrially. Some see PHAs as a beacon in a dark, plastics-filled world, with companies already trying to create an industry around such bio-based materials.

But PHAs have their limitations. They are made in bioreactors where communities of bacteria convert biorenewable carbon feedstocks, such as sugars, into the simplest form of PHA, called poly(3-hydroxybutyrate), or P3HB. Different carbon sources and bacteria can also make other PHA derivatives. These biosynthesis setups are currently expensive, relatively slow and hampered by their limited scalability and productivity.

In their Science paper, Chen and colleagues attack those limitations one by one, offering a novel, chemical synthetic pathway for making conventional and new PHAs with enhanced, tunable, mechanical and physical properties. These are the very characteristics that made petroleum plastics so ubiquitous in our world.

The CSU polymer chemists report that their new polymerization methodology is enabled by catalysts that directly polymerize a bio-sourced monomer called 8DL that exists in a form called stereo-isomers. The catalyzed polymerization produces orderly, crystalline, so-called "stereosequenced" PHAs. In the lab, the researchers showed their materials' ductility and toughness, and their ability to tune the structure and function of their materials.

"We wanted to solve the bottleneck issue," Chen said. "How can we develop the chemical catalysis pathway to this fantastic class of biodegradable plastics so that you have, basically, scalability, fast production and tunability to make different PHAs? ... That was the motivation."

This work built on previously published research that appeared in Nature Communications. Then, the researchers used their chemical synthesis pathway to make P3HB, one of 150 PHA biomaterials. But P3HB is relatively brittle, making it impractical for many petroleum plastics applications of today.

Chen stresses that he is not an expert in biosynthetic pathways for making PHAs. However, his lab is offering the technologically advantageous chemical catalysis approach to both existing and new PHA materials - which could play a big role in solving the plastics crisis of our generation.