adplus-dvertising
Connect with us

Science

Understanding Small-Angle X-Ray Scattering

Published

 on

Small angle X-ray scattering, or SAXS, is an experimental method where the intensity of the scattered X-rays is measured as a function of the scattering angle. The information obtained in a SAXS experiment can be used to recover information about the bulk microstructure within a sample and is commonly used to study condensed matter systems that are only partially ordered.

Image Credit: Juergen Faelchle/Shutterstock.com

One of the advantages of SAXS for the analysis of nanomaterials is that it can be used to analyze samples on a variety of length scales. In a typical SAXS experiment, the length scales measured can vary from the nanoscale to the mesoscale.

300x250x1

While for nanomaterial studies, some of the unique phenomena exhibited at the smallest length scales, such as enhanced thermal properties, are of primary interest, for many materials applications, the behavior across all length scales can be crucial for ensuring proper device performance.

SAXS Technique

In an X-ray scattering experiment, a sample is illuminated with an incident X-ray beam. Due to the interaction between the X-ray photons and atoms in the sample, some of the incident radiation will be scattered at different angles. Elastic scattering occurs when no energy exchange occurs between the incident X-ray photon and sample, so the scattered radiation is equal in energy to the incident radiation.

Some X-ray photons will be deflected or scattered at different angles to the incident X-ray radiation. By measuring the scattering angle and intensity of the X-ray radiation, information on the structural features of the sample can be recovered, such as particle sizes and distributions or the degree of disorder.

SAXS refers specifically to measuring the elastically scattered X-rays at small (~0 – 10°) angles. There is a related technique, wide-angle X-ray scattering (WAXS), that also measures elastically scattered radiation but at much wider scattering angles (> 10°).

Often, SAXS and WAXS experiments are performed together as changing the relative distance between the detector and the sample is sufficient to switch between a collection of wide or small-angle scattered radiation.

Many SAXS experiments are performed at advanced light source facilities such as synchrotrons as the weak nature of the scattering signal means that a high incident photon intensity is beneficial for improved signal-to-noise and reduced acquisition times in the measurement. However, there are a number of laboratory-based SAXS instruments as well, though acquisition times are typically very long.

Applications of SAXS

SAXS has several applications, including in the analysis of biological materials and nanomaterials. For nanoparticle analysis, SAXS is now often used as an in situ technique to monitor nanoparticle growth and formation. Understanding growth processes is an important part of developing synthesis strategies to grow nanoparticles in a controlled fashion and the structure of the nanoparticles determines their overall properties.

Nanoparticle sizing is a common application of SAXS due to the excellent spatial resolution of the technique that is achievable even in a laboratory environment. SAXS can also be used to extract concentration information from such samples.

SAXS is well-suited to in situ measurements of processes such as nanoparticle growth or materials synthesis as it requires minimal sample preparation and is compatible with a variety of sample types, including disordered solids and colloidal dispersions. In situ measurements require relatively short acquisition times to capture multiple images of the process as it occurs to see its evolution.

Biological applications account for a large number of SAXS studies, as SAXS can be used to determine the protein, nucleic acid and biopolymer structures and sizes.

As many biological systems undergo continual structural changes even at room temperature, one of the advantages of SAXS for biological imaging is that time-resolved variants of the technique can be used to capture processes such as protein folding in action. This makes SAXS an invaluable tool for not just understanding single structures in structural biology but the full landscape of how different conformers and structures are interconnected.

Outlook

As SAXS experiments use 2D detectors, a large amount of data is generated with each image recorded. Finding ways to reduce data sizes, speed up data processing and automate large parts of the analysis procedure has been very important in turning SAXS into a routine analytical tool. It is necessary to use some fitting and reconstruction procedures to convert from the recorded 2D image data to structural information such as particle sizes or distances.

Many of the algorithms for such procedures are available as relatively easy-to-use software packages for simple cases.

Brighter synchrotron sources, more efficient and sensitive detectors and greater degrees of automation of the experimental acquisition and data analysis will all help improve the throughput of SAXS measurements. With advances in nanoscale fabrication methods such as focused ion beams, there will continue to be a great demand for techniques such as SAXS that can characterize materials on the nanoscale reliably.

Time-resolved studies with SAXS are also likely to play an important role with the increasing availability of X-ray free-electron laser sources. Achieving very short (< 100 fs) time resolutions with high photon flux at synchrotrons can be very challenging.

Free-electron lasers, with their high peak brightnesses, also offer the ability to perform SAXS measurements on materials under extreme conditions to understand phenomena such as plasma formation and propagation in materials.

References and Further Reading

Giannini, C., Ladisa, M., Altamura, D., Siliqi, D., Sibillano, T., & Caro, L. De. (2016) X-ray Diffraction : A Powerful Technique for the Multiple-Length-Scale Structural Analysis of Nanomaterials. Crystals, 6, p. 87. https://doi.org/10.3390/cryst6080087

Shi, S., & Russell, T. P. (2018). Nanoparticle Assembly at Liquid – Liquid Interfaces : From the Nanoscale to Mesoscale. Advanced Materials, 30, p. 1800714. https://doi.org/10.1002/adma.201800714

Li, T., Senesi, A. J., & Lee, B. (2016). Small Angle X‑ray Scattering for Nanoparticle Research. Chemical Reviews, 116, pp. 11128–11180. https://doi.org/10.1021/acs.chemrev.5b00690

Garcia, P. R. A. F., Prymak, O., Grasmik, V., Pappert, K., Wlysses, W., Otubo, L., Epple, M., & Oliveira, C. L. P. (2020). SAXS investigation of the formation of silver nanoparticles and bimetallic silver – gold nanoparticles in controlled wet-chemical reduction synthesis. Nanoscale Advances, 2, pp. 225–238. https://doi.org/10.1039/c9na00569b

Pauw, B. R., Ka, C., & Thunemann, A. F. (2017). Nanoparticle size distribution quantification : results of a small-angle X-ray scattering inter-laboratory comparison research papers. Journal of Applied Crystallography, 50, pp. 1280–1288. https://doi.org/10.1107/S160057671701010X

Brosey, C. A., & Tainer, J. A. (2019). Evolving SAXS versatility : solution X-ray scattering for macromolecular architecture , functional landscapes , and integrative structural biology. Current Opinion in Structural Biology, 58, pp. 197–213. https://doi.org/10.1016/j.sbi.2019.04.004

Kluge, T., Rödel, M., Metzkes-ng, J., Pelka, A., Garcia, A. L., Prencipe, I., Rehwald, M., Nakatsutsumi, M., Mcbride, E. E., Schönherr, T., Garten, M., Hartley, N. J., Zacharias, M., Grenzer, J., Erbe, A., Georgiev, Y. M., Galtier, E., Nam, I., Lee, H. J., … Landstraße, B. (2018). Observation of Ultrafast Solid-Density Plasma Dynamics Using Femtosecond X-Ray Pulses from a Free-Electron Laser. Physical Review X, 8(3), p. 31068. https://doi.org/10.1103/PhysRevX.8.031068

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator 728x90x4

Source link

Continue Reading

Science

Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times

Published

 on


A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

300x250x1

According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Scientists Say They Have Found New Evidence Of An Unknown Planet… – 2oceansvibe News

Published

 on


In the new work, scientists looked at a set of trans-Neptunian objects, or TNOs, which is the technical term for those objects that sit out at the edge of the solar system, beyond Neptune

The new work looked at those objects that have their movement made unstable because they interact with the orbit of Neptune. That instability meant they were harder to understand, so typically astronomers looking at a possible Planet Nine have avoided using them in their analysis.

Researchers instead looked towards those objects and tried to understand their movements. And, Dr Bogytin claimed, the best explanation is that they result from another, undiscovered planet.

300x250x1

The team carried out a host of simulations to understand how those objects’ orbits were affected by a variety of things, including the giant planets around them such as Neptune, the “Galactic tide” that comes from the Milky Way, and passing stars.

The best explanation was from the model that included Planet 9, however, Dr Bogytin said. They noted that there were other explanations for the behaviour of those objects – including the suggestion that other planets once influenced their orbit, but have since been removed – but claim that the theory of Planet 9 remains the best explanation.

A better understanding of the existence or not of Planet 9 will come when the Vera C Rubin Observatory is turned on, the authors note. The observatory is currently being built in Chile, and when it is turned on it will be able to scan the sky to understand the behaviour of those distant objects.

Planet Nine is theorised to have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun.

You may be tempted to ask how an entire planet could ‘hide’ in our solar system when we have zooming capabilities such as the new iPhone 15 has, but consider this: If Earth was the size of a marble, the edge of our solar system would be 11 kilometres away. That’s a lot of space to hide a planet.

[source:independent]

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Dragonfly: NASA Just Confirmed The Most Exciting Space Mission Of Your Lifetime – Forbes

Published

 on


NASA has confirmed that its exciting Dragonfly mission, which will fly a drone-like craft around Saturn’s largest moon, Titan, will cost $3.35 billion and launch in July 2028.

Titan is the only other world in the solar system other than Earth that has weather and liquid on the surface. It has an atmosphere, rain, lakes, oceans, shorelines, valleys, mountain ridges, mesas and dunes—and possibly the building blocks of life itself. It’s been described as both a utopia and as deranged because of its weird chemistry.

Set to reach Titan in 2034, the Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. Here’s what else it will do:

300x250x1
  • Search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons.
  • Investigate the moon’s active methane cycle.
  • Explore the prebiotic chemistry in the atmosphere and on the surface.

Spectacular Mission

“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

It comes in the wake of the Mars Helicopter, nicknamed Ingenuity, which flew 72 times between April 2021 and its final flight in January 2023 despite only being expected to make up to five experimental test flights over 30 days. It just made its final downlink of data this week.

Dense Atmosphere

However, Titan is a completely different environment to Mars. Titan has a dense atmosphere on Titan, which will make buoyancy simple. Gravity on Titan is just 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.

function loadConnatixScript(document)
if (!window.cnxel)
window.cnxel = ;
window.cnxel.cmd = [];
var iframe = document.createElement(‘iframe’);
iframe.style.display = ‘none’;
iframe.onload = function()
var iframeDoc = iframe.contentWindow.document;
var script = iframeDoc.createElement(‘script’);
script.src = ‘//cd.elements.video/player.js’ + ‘?cid=’ + ’62cec241-7d09-4462-afc2-f72f8d8ef40a’;
script.setAttribute(‘defer’, ‘1’);
script.setAttribute(‘type’, ‘text/javascript’);
iframeDoc.body.appendChild(script);
;
document.head.appendChild(iframe);

loadConnatixScript(document);

(function()
function createUniqueId()
return ‘xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx’.replace(/[xy]/g, function(c) 0x8);
return v.toString(16);
);

const randId = createUniqueId();
document.getElementsByClassName(‘fbs-cnx’)[0].setAttribute(‘id’, randId);
document.getElementById(randId).removeAttribute(‘class’);
(new Image()).src = ‘https://capi.elements.video/tr/si?token=’ + ’44f947fb-a5ce-41f1-a4fc-78dcf31c262a’ + ‘&cid=’ + ’62cec241-7d09-4462-afc2-f72f8d8ef40a’;
cnxel.cmd.push(function ()
cnxel(
playerId: ’44f947fb-a5ce-41f1-a4fc-78dcf31c262a’,
playlistId: ‘aff7f449-8e5d-4c43-8dca-16dfb7dc05b9’,
).render(randId);
);
)();

The atmosphere is 98% nitrogen and 2% methane. Its seas and lakes are not water but liquid ethane and methane. The latter is gas in Titan’s atmosphere, but on its surface, it exists as a liquid in rain, snow, lakes, and ice on its surface.

COVID-Affected

Dragonfly was a victim of the pandemic. Slated to cost $1 billion when it was selected in 2019, it was meant to launch in 2026 and arrive in 2034 after an eight-year cruise phase. However, after delays due to COVID, NASA decided to compensate for the inevitable delayed launch by funding a heavy-lift launch vehicle to massively shorten the mission’s cruise phase.

The end result is that Dragonfly will take off two years later but arrive on schedule.

Previous Visit

Dragonfly won’t be the first time a robotic probe has visited Titan. As part of NASA’s landmark Cassini mission to Saturn between 2004 and 2017, a small probe called Huygens was despatched into Titan’s clouds on January 14, 2005. The resulting timelapse movie of its 2.5 hours descent—which heralded humanity’s first-ever (and only) views of Titan’s surface—is a must-see for space fans. It landed in an area of rounded blocks of ice, but on the way down, it saw ancient dry shorelines reminiscent of Earth as well as rivers of methane.

The announcement by NASA makes July 2028 a month worth circling for space fans, with a long-duration total solar eclipse set for July 22, 2028, in Australia and New Zealand.

Wishing you clear skies and wide eyes.

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Trending