Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Snowballs to soot: The clumping density of many things seems to be a standard

High school student Jessica Young checking the packing density of random aggregates of plastic spheres in a cylinder. Young's work as a summer intern at NIST contributed to a paper arguing that rigid aggregates like those she's testing tend to clump together at roughly the same density regardless of scale, from microscopic soot to large comets.
Credit: Baum/NIST
High school student Jessica Young checking the packing density of random aggregates of plastic spheres in a cylinder. Young's work as a summer intern at NIST contributed to a paper arguing that rigid aggregates like those she's testing tend to clump together at roughly the same density regardless of scale, from microscopic soot to large comets.

Credit: Baum/NIST

Abstract:
Particles of soot floating through the air and comets hurtling through space have at least one thing in common: 0.36. That, reports a research group at the National Institute of Standards and Technology (NIST), is the measure of how dense they will get under normal conditions, and it's a value that seems to be constant for similar aggregates across an impressively wide size range from nanometers to tens of meters.*

Snowballs to soot: The clumping density of many things seems to be a standard

Gaithersburg, MD | Posted on June 10th, 2014

NIST hopes the results will help in the development of future measurement standards to aid climate researchers and others who need to measure and understand the behavior of aerosols like carbon soot in the atmosphere.

Soot comes mostly from combustion and is considered the second biggest driver of global warming, according to NIST chemist Christopher Zangmeister. It is made up of small round particles of carbon about 10 or 20 nanometers across. The particles stick together randomly in short chains and clumps of a half dozen or more spheres. These, in turn, clump loosely together to form larger, loose aggregates of 10 or more which over a few hours will compact into a somewhat tighter ball which is atmospheric soot.

The interesting question for chemists studying carbon aerosols is how tight? How dense? Among other things, the answer relates to the balance of climate effects from soot: heating from light absorption versus cooling from light reflection.

The maximum packing density of objects is a classic problem in mathematics, which has been fully solved for only the simplest cases. The assumed density in models of atmospheric soot is 0.74, which is the maximum packing density of perfect spheres, such as billiard balls, in a given space. But when Zangmeister's team made measurements of the packing density of actual soot particles, the figure they got was 0.36. "We figured, man, we've got to be wrong, we're off by a factor of two," Zangmeister recalls, but "a bunch more measurements" convinced them that 0.36 was correct. Why?

Enter the summer help. Two students, one in college and one in high school, who were working with Zangmeister's group last summer were set to the task of modeling the packing question with little 6 mm plastic spheres sold for pellet guns. They glued thousands of random combinations of spheres together in clumps of from 1 to 12 spheres, and then filled every available size of graduated cylinders and hollow spheres with their assemblies, over and over, and over.

Their charted results, as a function of clump size, form a curve that levels off at … 0.36.

It gets better. Inspired by a book on the solar system he was reading with his son, Zangmeister checked NASA's literature. Comets are formed very much the same way as soot particles, except out of dust and ice, and they're a lot bigger. NASA's measurements on a collection of 20 comets estimate that packing density at between 0.2 and 0.4. So 0.36 may be an all-purpose value.**

NIST's interest in the nature of soot particles is driven by a desire to imitate them, according to Zangmeister. "It's amazing how much uncertainty there is in optical measurements of particles in the atmosphere. The reason for this uncertainty is rooted in something really important to NIST: there are no real methods for calibrations. You can calibrate any CO2 measurement using one of our Standard Reference Materials for CO2 in air, but there's no such thing as a bottle of standard aerosol or a standard aerosol generator. That's really at the heart of what we're trying to do: make a black material that simulates carbon that you can put into an aerosol and know it will come out the same way every time. It's a real materials chemistry project."

The agency is working with the National Research Council of Canada and Environment Canada on the project.

###

*C.D. Zangmeister, J.G. Radney, L.T. Dockery, J.T. Young, X. Ma, R. You and M.R. Zachariah., The packing density of rigid aggregates is independent of scale. PNAS Early Edition. Published online June 9, 2014. doi:10.1073/pnas.1403768111.

**0.36 is also very close to the reported values for compacted silicon dioxide monomers (ceramics industry) and pharmaceutical powders made from "microscale random aggregates."

####

About National Institute of Standards and Technology (NIST)
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

For more information, please click here

Contacts:
Michael Baum

301-975-2763

Copyright © National Institute of Standards and Technology (NIST)

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

The School of Materials at the University of Manchester utilise Deben’s mechanical stages to characterise structure and behaviour at the micro- and nano- scale July 25th, 2017

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Chemistry

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Tokyo Institute of Technology research: Antiaromatic molecule displays record electrical conductance July 19th, 2017

Harnessing light to drive chemical reactions July 19th, 2017

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

Carbon displays quantum effects July 13th, 2017

Laboratories

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

News laser design offers more inexpensive multi-color output: Design can control color, intensity of light by varying cavity architecture July 11th, 2017

Argonne National Laboratory’s Continuous ALD Technology Licensed Exclusively to Forge Nano July 7th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Ultrathin device harvests electricity from human motion July 23rd, 2017

The first light atomic nucleus with a second face July 20th, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Here's a tip: Indented cement shows unique properties: Rice University models reveal nanoindentation can benefit crystals in concrete July 20th, 2017

Discoveries

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Announcements

The School of Materials at the University of Manchester utilise Deben’s mechanical stages to characterise structure and behaviour at the micro- and nano- scale July 25th, 2017

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Environment

Researchers revolutionize vital conservation tool with use of gold nanotechnology and lasers: Cryopreservation study results have sweeping implications for wildlife conservation and human health July 15th, 2017

Bacteria-coated nanofiber electrodes clean pollutants in wastewater July 1st, 2017

Nanostructures taste the rainbow: Combining nanophotonics and thermoelectrics, engineers at Caltech generate materials capable of distinguishing between tiny differences in wavelengths of light June 30th, 2017

New photoacoustic technique detects gases at parts-per-quadrillion level June 30th, 2017

Aerospace/Space

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

National Space Society Governor Scott Pace Named to National Space Council as Executive Secretary July 18th, 2017

National Space Society Supports VP Pence's Call for Constant Low-Earth Orbit Human Presence Leading to the Settlement of Space July 13th, 2017

Thinking thin brings new layering and thermal abilities to the semiconductor industry: In a breakthrough for the semiconductor industry, researchers demonstrate a new layer transfer technique called "controlled spalling" that creates many thin layers from a single gallium nitride July 11th, 2017

Research partnerships

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

GLOBALFOUNDRIES and VeriSilicon To Enable Single-Chip Solution for Next-Gen IoT Networks: Integrated solution leverages GF’s 22FDX® technology to decrease power, area, and cost for NB-IoT and LTE-M applications July 14th, 2017

Carbon displays quantum effects July 13th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project