Understanding Material Characteristics Through Signature Traits From Helium Pycnometry

Although helium pycnometry is generally the method of choice for skeletal density measurements of porous materials, few studies have provided a wide range of case studies that demonstrate how to best interpret raw data and perform measurements using it. The examination of several different classes of materials yielded signature traits from helium pycnometry data that are highlighted. Experimental parameters important in obtaining the most precise and accurate value of skeletal density from the helium pycnometer are as high as possible percent fill volume and good thermostability. The degree of sample activation is demonstrated to affect the measured skeletal density of porous zeolitic, carbon, and hybrid inorganic–organic materials. In the presence of a significant amount of physisorbed contaminants (water vapor, atmospheric gases, residual solvents, etc.), which was the case for ZSM-5, MIL-53, and F400, but not ZIF-8, the skeletal density tended to be overestimated in the low percent volume region. In addition, the kinetic data (i.e., skeletal density vs measurement cycle) reveals distinctive traits for a properly activated vs a nonactivated sample for all examined samples: activated samples with a significant amount of mass loss show a curved down plot that eventually reaches the equilibrium value, whereas nonactivated, nonporous, or extremely hydrophobic samples exhibit a flat line. This work illustrates how helium pycnometry can provide information about the structure of a material, and that, conversely, when the structure of the material and its percent mass loss after activation (amount of physisorbed contaminants) are known, the behavior of activated and nonactivated samples in terms of skeletal density, percent fill volume, and measurement cycle can be predicted.

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ESA Planning To Mine The Moon

Last week, the European Space Agency (ESA) has announced the signing of a one-year contract with ArianeGroup, a European aerospace consortium. The intention is part of a bid to look at the feasibility of mining on the surface in the search for natural resources and to extract lunar soil, known as regolith. While the Moon may look like a barren wasteland, its dust-like soil contains oxygen and water, and many space agencies believe that mining there would be the first step towards setting up permanent colonies or bases. If the feasibility study concludes that it is possible to carry out the mining, the ESA is eyeing up a 2025 start date for the mission to begin. ArianeGroup has made it clear that the mission does not involve sending humans to the Moon, focusing on robotic equipment. ArianeGroup CEO, André-Hubert Roussel described the signing of the contract as an important milestone: “In this year, marking the fiftieth anniversary of Man’s first steps on the Moon, ArianeGroup will thus support all current and future European projects, in line with its mission to guarantee independent, sovereign access to space for Europe.” Mining the Moon would be hugely beneficial to future deep space exploration missions, with the lunar body being used like a refuelling station for longer haul missions. The resources in regolith could then be used to create life-support and fuel systems, and essential part of any future space voyages. ArianeGroup will be working with a German start-up called PTScientists, which will design and build the lunar lander, along with Belgian firm Space Applications Services, which will provide the communication infrastructure and ground control facilities. As well as the valuable regolith, the Moon is also rich in helium-3 isotopes. The ESA claims that these isotopes could be used in the production of safer nuclear energy in fusion reactors. Helium-3 isotopes are not radioactive and do not produce dangerous waste products and they could also be used for fuelling spacecraft in the future. Director of Human and Robotic Exploration at ESA, Dr David Parker said: “The use of space resources could be a key to sustainable lunar exploration and this study is part of ESA’s comprehensive plan to make Europe a partner in global exploration in the next decade – a plan we will put to our Ministers for decision later this year at the Space19+ Conference.” There is significant debate amongst experts as to whether or not Moon mining is economically feasible. According to professor of planetary science and astrobiology at Birkbeck College, London, Ian Crawford, it is highly unlikely. Professor Crawford believes that transporting the ore from the Moon back to Earth would be economically untenable and that it would cost more to mine the Moon than to construct renewable energy facilities to power the planet. He added “It doesn’t make sense, the whole helium-3 argument. Strip-mining the lunar surface over hundreds of square kilometres would produce lots of helium-3, but the substance is a limited resource”, explained Crawford. “Once you mine it it’s gone.” He did concede, however, that it may be a different story when mining for other materials, such as uranium and thorium, as well as those we may not yet be aware of. “It’s entirely possible that when we really explore the moon properly we will find higher concentrations of some of these materials … materials that are not resolvable by orbital remote sensing,” he added.

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‘New Invisible Hand’ Is Guiding Commodities; Copper Is The Big Winner – Gianni Kovacevic

If you love gold, look at copper, said CopperBank executive chairman Gianni Kovacevic, pointing to a surge in demand. “There is a new invisible hand for commodities. And within this hinge of history, we are going go to about 50% of final energy as electrification from the current 19% and it will all happen in 30 years and it will be enabled with metals. Copper is the big winner,” Kovacevic told Kitco News on the sidelines of the Vancouver Resource Investment Conference. Kovacevic keeps his focus on copper but says that investors don’t have to choose between copper and gold. “When you look at the big copper-gold mines, they give us a lot of gold output,” he said. “I always tell my friends that love gold to focus on the copper. You get all the gold as a byproduct and you’re going to get all that benefit. You don’t necessarily have to look at primary gold deposits, which are harder and harder to find.” Another interesting investment Kovacevic is looking at is helium — yes, party balloons, but not quite… “People associate helium with balloons at parties. It is not the case. It’s a high-tech commodity. You’ll find it in MRIs, the high-tech industry, cooling for servers, and nuclear power plants,” he said. And there is a big shortage of it around, with one of the biggest reserves located conveniently in the U.S. “[Supply] is falling off a cliff. We haven’t found a lot of new helium reserves and so it trades right now at $279 per MCF when natural gas is at $4-$5, which is a huge differentiator,” Kovacevic noted. “One of the most prolific areas is on the New Mexico-Arizona border. That’s where a lot of the high grade, high-quality helium reserves have come from.”

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Physicists Created Quantum Structures That May Have Birthed Dark Matter

Some cosmologists have predicted the existence of “walls bounded by strings” in the aftermath of the Big Bang, and now a team of physicists have created these quantum structures on Earth for the first time.

Physicists in Finland have experimentally created quantum structures that some cosmologists believe were formed seconds after the Big Bang, and may have given birth to dark matter. As detailed in paper recently published in Nature Communications, the researchers at the Low Temperature Laboratory at Aalto University were able to create quantum objects known as half-quantum vortices and walls bounded by strings in superfluid helium. A superfluid is a liquid that has no viscosity and is thus able to flow without losing its energy. Although half-quantum vortices were created in superfluid helium for the first time a few years ago, this is the first time that researchers have demonstrated they are able to survive phase transitions into different types of superfluidity. The physicists also demonstrated that after a certain superfluid phase transition these half-quantum vortices form a new quantum object known as walls bounded by strings, which were first predicted by cosmologists decades ago, but never realized in a lab until now. The breakthrough may have applications for testing theories about the early universe, especially certain theories about the origin of dark matter. But before we dive into the significance of the research it will help to have a little background.


ll matter is subject to phase transitions that can be induced by varying the conditions (pressure, temperature, etc.) in a system. An example of a phase transition familiar to all of us is when liquid water transitions to a solid (ice) at 32 degrees Fahrenheit at sea level. Each time a phase transition occurs in a material, it alters the material’s symmetry. Symmetry is the most fundamental concept in physics, and ultimately constrains how particles can interact with one another. In physics, symmetry can be thought of as the properties of a system that stay the same when some change is applied to that system. This is pretty abstract, so consider an example given by University of Oregon professor James Schombert in which he likens pure symmetry to spinning a coin. “The coin has two states [heads or tails], but while it is spinning neither state is determined, and yet both states exist,” Schombert wrote. “The coin is in a state of both/or. When the coin hits the floor, the symmetry is broken (it’s either heads or tails) and energy is released in the process [as noise].”


Breaking symmetry during phase transitions can produce topological defects, artefacts from the original ground state that remain after the system has undergone a phase transition. Consider again the case of liquid water turning into ice. As the temperature drops, the water begins to turn into ice crystals at many different locations, and those crystals grow until they begin to intersect with the other ice crystals. Each of those ice crystals independently have an ordered crystalline structure, but this pattern is broken at the boundaries where they intersect with other ice crystals. The jagged boundaries of the ice crystals are an example of topological defects. At extremely low temperatures, topological defects can take the form of quantum objects such as half-quantum vortices and domain walls. To see if these quantum objects can survive helium’s phase transition between different types of superfluids, the researchers cooled helium-3 down to less than half a millikelvin above absolute zero (theoretically the lowest possible temperature). Depending on the ambient pressure, helium-3 transitions into a superfluid at temperatures between one and three millikelvin.

An artist’s depiction of “walls bounded by strings.” Image: Ella Maru Studios

Half-quantum vortices can be thought of as a perpetual whirlpool of helium. According to Jere Mäkinen, a doctoral student and the lead author of the new research, these half-quantum vortices can only be created during helium’s transition into a superfluid in the polar phase. “Polar” here means that the pairs of tightly-bonded helium-3 atoms that are formed during the phase change have an angular momentum, or rotation, that is aligned either “up” or “down.” By orienting itself one way instead of the other during a phase transition, the superfluid helium-3 breaks a fundamental symmetry, which results in the formation of the vortices. While the formation of half-quantum vortices in helium-3 had been demonstrated in previous experiments, what Mäkinen and his colleagues wanted to know was whether the vortices would survive a phase transition into two “deeper” phases of superfluidity that are characterized by polar distortion, known as polar distortion-A (pdA) and polar distortion-B (pdB). As Mäkinen told me in an email, not only did the half-quantum vortices survive helium’s transition into both of the polar distorted superfluid phases, which had never been seen before, but the fact that the vortices survived the transition to pdB meant that “walls bounded by strings” must have been created in the process. Unlike a normal wall we encounter in day-to-day life, these quantum walls do not block the flow of the helium vortices but rather alter the magnetic properties of the helium in the vortex. This was the first time that walls bounded by strings, also known as domain walls, were created in a laboratory setting.


The dynamics of symmetry-breaking and the topological defects that are produced during phase transitions are fundamental to how some cosmologists explain how the universe formed directly after the Big Bang. The further back in time we go toward the Big Bang, the matter in the universe gets hotter, and more symmetric. This process can be extrapolated back to the earliest instance, a theoretical point known as the “grand unification.” This might be thought of as the original phase, which rapidly underwent a series of transitions in the first few seconds after the Big Bang until the universe gradually cooled and formed the matter that we’re all familiar with today. The problem for cosmologists is that the extremely high temperatures and pressures that dominated the first microseconds after the Big Bang would have prevented the creation of permanent particles. These could only come about later, after the universe had sufficiently cooled.What cosmologists want to understand, then, is the dynamics of the phase transitions in the early universe that allowed for the emergence of the fundamental forces (weak, strong, electromagnetic) and finally the particles that make up the ordinary matter we’re all familiar with. According to Tanmay Vachaspati, a theoretical cosmologist at Arizona State University, there is a grand unified model that incorporates vortices and walls as the precursors of axions, a leading particle candidate for dark matter. Although the vortices and domain walls would be destroyed in the process of producing the axions, the resulting dark matter would be the scaffolding upon which the large scale structures of the universe, such as galaxies, are built. Although this theory about vortices in the early universe and their role in the macrostructure of the universe has been around for decades, it lacked any clear path to an experimental test. The theory about the role of half-quantum vortices in the formation of the macrostructure of the universe is by no means widely accepted. Mäkinen said that many leading cosmologists have abandoned this idea in favor of quantum fluctuations and inflation as the explanation for the large-scale structure of the universe. Nevertheless, Vachaspati that since the physics demonstrated in the lab would carry over to the universe at large, the results of the experiments in the Aalto lab are of interest to cosmologists. In this respect, Mäkinen and his colleagues have created a way for cosmologists to experimentally recreate properties of the early universe predicted in some cosmological models. Going forward, these experimental tests of cosmological theories could greatly advance our understanding of why the universe formed the way it did—or at least help rule out some alternative theories.


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The Gasturbine Modular Helium Reactor

The Gas Turbine – Modular Helium Reactor (GT-MHR) couples a High Temperature
Gas-cooled Reactor (HTGR) with a Brayton power conversion cycle to produce
electricity at high efficiency. It is based on HTGR technology developed over the past
40 years that includes the design, construction and operation of seven HTGR plants.
The GT-MHR satisfies the Gen-IV goals of passive safety, good economics, high
proliferation resistance, and improved environmental characteristics including reduced
waste and better fuel utilization than the current generation of nuclear power plants.
Because of its capability to produce high coolant outlet temperatures (at least 850°C
with potential for still higher temperature), the modular helium reactor system can also
efficiently produce hydrogen by high temperature electrolysis or thermochemical water
splitting. The technology embodied in the GT-MHR concept has high potential, with
modest further development work, to meet the requirements for the Next Generation
Nuclear Plant (NGNP) demonstration project planned to be built at the Idaho National
Engineering and Environmental Laboratory (INEEL). The NGNP objectives are to
demonstrate passive safety, licensing of new nuclear plants, use of the Brayton cycle for
high efficiency electricity generation and use of high temperature nuclear heat for
production of hydrogen.



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