Tetrahedrality is key to the uniqueness of waterWater holds a…

Tetrahedrality is key to the uniqueness of water

Water holds a special place among liquids for its unusual properties, and remains poorly understood. For example, it expands just upon the freezing to ice, and becomes less viscous under compression, around atmospheric pressure. Rationalizing these oddities is a major challenge for physics and chemistry. Recent research led by The University of Tokyo’s Institute of Industrial Science (IIS) suggests they result from the degree of structural ordering in the fluid.

Water belongs to a class of liquids whose particles form local tetrahedral structures. The tetrahedrality of water is a consequence of hydrogen bonds between molecules, which are constrained to fixed directions. In a study in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), the researchers investigated why the physical properties of water – as expressed by its phase diagram – are so remarkable, even compared with other tetrahedral liquids, such as silicon and carbon.

Tetrahedral liquids are often simulated by an energy potential named the SW model. The liquid is assumed to contain two phases – a disordered state that has high rotational symmetry, and a tetrahedrally ordered state that does not – in thermodynamic equilibrium. Despite its simplicity, the model accurately predicts anomalous liquid behaviors. The two-state property is controlled by the parameter lambda (λ), which describes the relative strength of pairwise and three-body intermolecular interactions. The higher λ is, the degree of tetrahedral order increases.

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Space Station Science Highlights: Week of Mar 19, 2018

ISS – Expedition 55 Mission patch.

March 28, 2018

International Space Station (ISS). Image Credits: NASA/STS-134

The crew members aboard the International Space Station were busy last week with many hours of scientific operations as they awaited the arrival of three new crew members and planned for an upcoming spacewalk.

NASA’s Ricky Arnold, Drew Feustel and Oleg Artemyev, a cosmonaut out of Roscosmos, arrived to the space station after launching inside the Soyuz MS-08 spacecraft Wednesday March 21 from the Baikonur Cosmodrome in Kazakhstan. They joined the rest of the Expedition 55 crew, who have been living and working aboard the space station since Dec. 19.

Image above: Mizuna and Green Lettuce growing within plant pillows as a part of the Veg-03 investigation. Image Credit: NASA.

Take a look at some of the science that happened this week aboard your orbiting laboratory:

Investigation tests adjustable lighting options to encourage better sleep

The hazards of lost sleep can range from on-the-job errors to chronic disease. People all around the world experience disruptions in circadian rhythm, or the body’s natural regulator for sleep and wake cycles based on a 24-hour schedule, every day. This instinctual process can be disrupted by abnormal work schedules, extensive traveling between time zones, and by daily life for space crew members, who could experience 16 sunrises a day.

The Testing Solid State Lighting Countermeasures to Improve Circadian Adaptation, Sleep, and Performance During High Fidelity Analog and Flight Studies for the International Space Station (Lighting Effects) investigation studies the impact of the change from fluorescent light bulbs to solid-state light-emitting diodes (LEDs) with adjustable intensity and color and aims to determine if the new lights can improve crew circadian rhythms, sleep, and cognitive performance.

Animation above: The Advanced Combustion Microgravity Experiment (ACME) investigation is a set of studies of gaseous flames to be conducted in the Combustion Integration Rack (CIR), one of which being Electric-Field Effects on Laminar Diffusion Flames (E-FIELD Flames). In E-FIELD Flames, an electric field with voltages as high as 10,000 volts is established between the burner and a mesh electrode. Animation Credit: NASA.

Last week, crew members completed daily sleep logs, noting sleep patterns and periods of wakefulness. Information collected during this investigation will be used to develop more efficient lighting both in space and on Earth. Learn more about adjusting to sleep disruptions here.

Instrument starts collection of data

NASA’s Total and Spectral Solar Irradiance Sensor, or TSIS-1, measures the sun’s energy input to Earth. Various satellites have captured a continuous record of this solar energy input to Earth since 1978. TSIS-1 sensors advance previous measurements with three times the accuracy, enabling scientists to study the sun’s natural influence on Earth’s ozone layer, atmospheric circulation, clouds, and ecosystems. These observations are essential for a scientific understanding of the effects of solar variability on the Earth system.

Last week marks the completion of the check-out process of the TSIS instrument since its arrival on the SpaceX CRS-13 and the start of the five-year data collection process.

Sensors track astronaut sleeping habits

In addition to studying alternative lighting options to improve sleeping habits in space, researchers are also examining changes in in circadian rhythms in humans during long-term spaceflight. The Circadian Rhythms investigation provides important insight into adaptations of the human autonomic nervous system in space over time and helps to improve physical exercise plans, rest- and work shifts and fosters adequate workplace illumination during future spaceflight.

Animation above: JAXA astronaut Norishige Kanai conducts maintenance on the Fluid Integration Rack (FIR). Animation Credit: NASA.

Last week, a crew member began the experiment by donning the Thermolab Double sensors, a wearable sensor, and then removing it 36 hours later.

Camera records full Earth rotation for television series

The space station offers vantage points not available from any other location on Earth. The National Geographic Channel–Virtual Reality Educational Video for Television Series–”One Strange Rock” (One Strange Rock Virtual Reality) investigation brings the space station into homes by capturing day-in-the-life style footage of the crew aboard the station. Each episode in the series will feature a different crew member and address different natural history and solar system topics, raising awareness of the space program and the Earth as a life-support system.

Last week, the crew opened all Cupola Window shutters and deployed the NanoRacks Vuze Camera to record views for one full Earth rotation, including sunrise and sunset.

Space to Ground: Night Launch: 03/23/2018

Video Credit: NASA Johnson.

Other work was done on these investigations: Crew Earth Observations, Veg-03,  MagVector (supporting WiseNet), Space Headaches, Transparent Alloys, DOSIS-3D, EIISS,  VESSEL ID, ACME E-FIELD Flames, Two Phase Flow, Fluids Integrated Rack (FIR), Manufacturing Device, Rodent Research-6, and Tropical Cyclone.

Related links:

Lighting Effects: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013

Total and Spectral Solar Irradiance Sensor (TSIS-1): http://www.nasa.gov/tsis-1

SpaceX CRS-13: https://www.nasa.gov/mission_pages/station/research/news/resupply_critical_science_to_ISS

Circadian Rhythms: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=869

One Strange Rock Virtual Reality: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7598

Cupola: https://www.nasa.gov/mission_pages/station/structure/elements/cupola.html

Crew Earth Observations: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=84

Veg-03: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1159

MagVector: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1070

Space Headaches: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=174

Transparent Alloys: https://www.eusoc.upm.es/transparent-alloys/

DOSIS-3D: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=177

EIISS: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7565

VESSEL ID: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=737

ACME E-FIELD Flames: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2058

Two Phase Flow: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1034

Manufacturing Device: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1934

Rodent Research-6: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7423

Tropical Cyclone: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1712

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Animations (mentioned), Video (mentioned), Text, Credits: NASA/Erling Holm/Yuri Guinart-Ramirez, Lead Increment Scientist Expeditions 55 & 56.

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