Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

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

Animal study shows flexible, dissolvable silicon device promising for brain monitoring: Other applications include post-operative observation for vascular, cardiac, and orthopaedic procedures, finds Penn study May 5th, 2016

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Laboratories

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

NREL finds nanotube semiconductors well-suited for PV systems April 27th, 2016

Chemistry

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

New tool allows scientists to visualize 'nanoscale' processes May 4th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Animal study shows flexible, dissolvable silicon device promising for brain monitoring: Other applications include post-operative observation for vascular, cardiac, and orthopaedic procedures, finds Penn study May 5th, 2016

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Discoveries

Animal study shows flexible, dissolvable silicon device promising for brain monitoring: Other applications include post-operative observation for vascular, cardiac, and orthopaedic procedures, finds Penn study May 5th, 2016

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Unique nano-capsules promise the targeted drug delivery: Russian scientists created unique nano-capsules for the targeted drug delivery May 5th, 2016

Announcements

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Unique nano-capsules promise the targeted drug delivery: Russian scientists created unique nano-capsules for the targeted drug delivery May 5th, 2016

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

Animal study shows flexible, dissolvable silicon device promising for brain monitoring: Other applications include post-operative observation for vascular, cardiac, and orthopaedic procedures, finds Penn study May 5th, 2016

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Environment

Team builds first quantum cascade laser on silicon: Eliminates the need for an external light source for mid-infrared silicon photonic devices or photonic circuits April 21st, 2016

Atomically thin sensor detects harmful air pollution in the home April 18th, 2016

Catalyst could make production of key chemical more eco-friendly April 10th, 2016

Nanoporous material's strange "breathing" behavior April 7th, 2016

Aerospace/Space

Physicists detect the enigmatic spin momentum of light April 26th, 2016

Team builds first quantum cascade laser on silicon: Eliminates the need for an external light source for mid-infrared silicon photonic devices or photonic circuits April 21st, 2016

All powered up: UCI chemists create battery technology with off-the-charts charging capacity April 21st, 2016

Acclaimed Science Fiction Author Dr. Jerry Pournelle Wins the National Space Society Robert A. Heinlein Award April 13th, 2016

Research partnerships

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

Making invisible physics visible: The Jayich Lab has created a new sensor technology that captures nanoscale images with high spatial resolution and sensitivity May 2nd, 2016

Cooling graphene-based film close to pilot-scale production April 30th, 2016

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







Car Brands
Buy website traffic