The U.S. Naval Research Laboratory has developed a method of using hyperthermal ion implantation as a means to substitutionally dope graphene with nitrogen atoms to produce a low-defect film with a tunable band structure.

NRL said Monday the HyTII system was used to implant nitrogen into graphene to achieve doping via a direct substitution.

“In our study, we determined the range of hyperthermal ion energies that yielded the highest fraction of nitrogen doping, while minimizing defects,” said Cory Cress, NRL materials research engineer.

Adam Friedman, NRL research physicist, said the measurements of the devices worked to fabricate a graphene film with tunable bandgap, low defect density and high stability.

He also hypothesized the system has a potential for electronic or spintronic applications.

NRL noted the nitrogen implantation dose affects the transition of doping from strong to weak and alters the properties of the film.

The results of the study can be found on the ACS Nano 10 — where the fabrication method and efficient doping energy range were discussed — and the Physical Review B: Rapid Communications 93, NRL added.

Energy Secretary Ernest Moniz met with energy ministers from Canada and Mexico at the 7th Clean Energy Ministerial and Mission Innovation Ministerial meetings in San Francisco to discuss the programs launched by the three countries to address climate change.

Moniz held the meetings with Jim Carr, Canada’s natural resources minister; and Pedro Joaquin Coldwell, Mexico’s energy secretary; to review the efforts of the three North American countries to meet clean energy objectives, the Energy Department said Friday.

These include investments in research and development programs related to clean energy over the next five years, implementation of the ISO 50001 standard by energy companies and launch of a study that aims to determine the operational impacts once solar, wind, hydro and other renewable energy sources are integrated with electricity grids.

“Trilateral energy cooperation between the United States, Canada, and Mexico is crucial to advancing our energy security and growing low-carbon economies,” Moniz said.

“Today’s announcement by the North American energy ministers demonstrates our collective support for CEM7 and Mission Innovation as tools to implement our countries’ commitments made in Paris to combat climate change by developing and deploying clean energy technologies.”

A Congressional Budget Office report estimates annual costs linked to hurricane damage driven by climate change and development in coastal areas to climb from $28 billion under current conditions to approximately $39 billion by 2075.

CBO said in the report published Thursday that annual federal spending on disaster relief and recovery missions as a result of potential increases in hurricane damage would grow from $18 billion or 0.10 percent of the gross domestic product in 2016 to approximately $24 billion or 0.13 percent of GDP by 2075.

According to the report, the number of U.S. citizens who live in counties that are vulnerable to hurricane damage will likely hit 10 million over the next 59 years, up from 1.2 million under present conditions.

The agency noted that investments in structural changes that seek to lessen susceptibility to hurricanes, reduction in greenhouse gas emissions and measures to allow private entities and agencies at both state and local government levels to shoulder hurricane damage costs might help reduce federal spending on disaster relief efforts.

CBO estimated hurricane damage based on the frequency of hurricanes, sea levels in various states, per capita income as well as the population in coastal areas.