Carbon is the fourth-most-abundant element in the universe and takes on a wide variety of forms, called allotropes, including diamond and graphite. Scientists at Carnegie’s Geophysical Laboratory are part of a team that has discovered a new form of carbon, which is capable of withstanding extreme pressure stresses that were previously observed only in diamond. […]Read more...
Carbon is the fourth-most-abundant element in the universe and takes on a wide variety of forms, called allotropes, including diamond and graphite. Scientists at Carnegie’s Geophysical Laboratory are part of a team that has discovered a new form of carbon, which is capable of withstanding extreme pressure stresses that were previously observed only in diamond. This breakthrough discovery is published by Physical Review Letters.
The team was led by Stanford’s Wendy L. Mao and her graduate student Yu Lin and includes Carnegie’s Ho-kwang (Dave) Mao, Li Zhang, Paul Chow, Yuming Xiao, Maria Baldini, and Jinfu Shu. The experiment started with a form of carbon called glassy carbon, which was first synthesized in the 1950s, and was found to combine desirable properties of glasses and ceramics with those of graphite. The team created the new carbon allotrope by compressing glassy carbon to above 400,000 times normal atmospheric pressure.
This new carbon form was capable of withstanding 1.3 million times normal atmospheric pressure in one direction while confined under a pressure of 600,000 times atmospheric levels in other directions. No substance other than diamond has been observed to withstand this type of pressure stress, indicating that the new carbon allotrope must indeed be very strong.
However, unlike diamond and other crystalline forms of carbon, the structure of this new material is not organized in repeating atomic units. It is an amorphous material, meaning that its structure lacks the long-range order of crystals. This amorphous, superhard carbon allotrope would have a potential advantage over diamond if its hardness turns out to be isotropic—that is, having hardness that is equally strong in all directions. In contrast, diamond’s hardness is highly dependent upon the direction in which the crystal is oriented.
“These findings open up possibilities for potential applications, including super hard anvils for high-pressure research and could lead to new classes of ultradense and strong materials,” said Russell Hemley, director of Carnegie’s Geophysical Laboratory.
This research was funded, in part, by the Department of Energy’s Office of Basic Energy Sciences Division of Materials Sciences and Engineering, EFree, HPCAT, where some of the experiments were performed, is funded by DOE-BES, DOE-NNSA, NSF, and the W.M. Keck Foundation. APS, where some of the experiments were performed, is supported by DOE-BES.
Boston Children’s Hospital physicians report the first cases of children benefiting from 3D printing of their anatomy before undergoing high-risk brain procedures. The four children had life-threatening cerebrovascular malformations (abnormalities in the brain’s blood vessels) that posed special treatment challenges. Reporting online today in the Journal of Neurosurgery: Pediatrics, the physicians describe the use of […]Read more...
Boston Children’s Hospital physicians report the first cases of children benefiting from 3D printing of their anatomy before undergoing high-risk brain procedures. The four children had life-threatening cerebrovascular malformations (abnormalities in the brain’s blood vessels) that posed special treatment challenges.
Reporting online today in the Journal of Neurosurgery: Pediatrics, the physicians describe the use of 3D printing and synthetic resins to create custom, high-fidelity models of the children’s vessel malformations along with nearby normal blood vessels. In some cases, the surrounding brain anatomy was also printed.
“These children had unique anatomy with deep vessels that were very tricky to operate on,” says Boston Children’s neurosurgeon Edward Smith, MD, senior author of the paper and co-director of the hospital’s Cerebrovascular Surgery and Interventions Center. “The 3D-printed models allowed us to rehearse the cases beforehand and reduce operative risk as much as we could.”
The children ranged in age from 2 months to 16 years old. Three of the four children had arteriovenous malformations (AVMs), in which tangles of arteries and veins connect abnormally, and were treated surgically.
“AVMs are high-risk cases and it’s helpful to know the anatomy so we can cut the vessels in the right sequence, as quickly and efficiently as possible,” says Smith. “You can physically hold the 3D models, view them from different angles, practice the operation with real instruments and get tactile feedback.”
The 2-month-old infant had a rare vein of Galen malformation in which arteries connect directly with veins—bypassing the capillaries—and was treated with an interventional radiology technique to seal off the malformed blood vessels from the inside.
“Even for a radiologist who is comfortable working with and extrapolating from images on the computer to the patient, turning over a 3D model in your hand is transformative,” says Darren Orbach, MD, PhD, chief of Interventional and Neurointerventional Radiology at Boston Children’s and co-director of the Cerebrovascular Surgery and Interventions Center. “Our brains work in three dimensions, and treatment planning with a printed model takes on an intuitive feel that it cannot otherwise have.”
The life-sized and enlarged 3D models were created in collaboration with the Boston Children’s Hospital Simulator Program (SIMPeds) using brain magnetic resonance (MR) and MR arteriography data from each child. Measurements of the models showed 98 percent agreement with the children’s actual anatomy.
All four children’s malformations were successfully removed or eliminated with no complications. When two of the AVM patients were compared with controls who did not have 3D-printed models—matched for age, size and type of AVM, surgeon and operating room—those with 3D models had their surgical time reduced by 12 percent (30 minutes). (Actual surgical time was 254 and 257 minutes for the cases with 3D models and 285 and 288 minutes for the controls.) Even a 30-minute reduction is significant for children who are especially sensitive to anesthesia.
Smith and Orbach are continuing to use 3D models for their trickier cases. “3D printing has become a regular part of our process,” says Smith. “It’s also a tool that allows us to educate our junior colleagues and trainees in a way that’s safe, without putting a child at risk.”
SIMPeds director Peter Weinstock, MD, PhD, was first author on the paper; co-authors were Orbach, Sanjay Prabhu, MBBS, FRCR, and Katie Flynn, BS, ME, all of Boston Children’s Hospital. The study was supported by the Lucas Warner AVM Research Fund and The Kids At Heart Neurosurgery Research Fund.