Trifluoroacetate (TFA) is an ultrashort-chain perfluorinated alkanoic acid anion that is exceptionally stable in the environment. Initial research focused on the potential for hydrofluorocarbon (HFC) refrigerants to create TFA in the atmosphere, (1?3) but it has since been shown that TFA arises from many additional sources including fluorochemical production facilities, (4?6) degradation of fluoropolymers, (7) inhaled anesthetics, (8) specific pesticides with a trifluoromethyl group, (9) certain pharmaceuticals, (5) and fluorochemical-based fire-fighting foams. (10) TFA produced from HFC degradation in the atmosphere was expected to partition into water, ionize, and wash out of the atmosphere. Since the main precursor compounds were globally distributed due to their long atmospheric lifetimes (e.g., 14.4 years for HFC-134a), (2) TFA was expected to appear in regions with no local sources of TFA. The concern was that TFA could accumulate in certain terminal waterbodies that lack any significant outflow. (11,12) Since TFA is weakly phytotoxic, (13,14) the concentration of TFA could ultimately achieve toxic concentrations in the future. Furthermore, if problems arise, then the effects could persist for extended time periods due to the stability of TFA.
Attention shifted away from TFA to the longer fluorinated chain acids in the late 1990s and early 2000s when the longer chain perfluorinated compounds, such as perfluorooctanesulfonic acid (PFOS), were discovered to be ubiquitous in the environment. Unlike TFA, these longer perfluorinated acids had both high animal toxicity and the potential to bioaccumulate, so they represented a more immediate risk to both humans and the environment. Research into TFA dwindled with only a few recent ambient measurements being reported, (15,16) while most of the remaining research focused on suspected point sources such as fluorochemical production plants (4?6) and fire-fighting training sites. (10)

However, the use of first-generation fluorocarbon refrigerants, such as HFC-134a, continued to rise and the atmospheric concentrations climbed along with them. Between 1998 and 2021, the atmospheric concentrations of HFC-134a increased approximately14-fold from 8.7 to 121 ppt at the Mona Loa Observatory, Hawaii, (17) so the amount of TFA formed in the atmosphere would be expected to increase by a similar value. Furthermore, HFC-134a is being phased out and its apparent replacement, namely hydrofluoroolefin-1234yf (HFO-1234yf), has a higher product yield for TFA (near 100%) (18) compared to HFC-134a (approximately 30% depending on pressure and temperature (19)), which would also suggest that more TFA will be forming in the atmosphere.

Figure 1. Location of sampling sites along a transect upwind and downwind of major metropolitan areas in Northern California. The predominant surface wind climatology is marked with the white dashed lines. (27) The open symbols represent streams that were originally sampled in 1998 that were dry in 2021. Satellite photo from Google Earth.

Figure 2. TFA concentrations during the two sampling periods and different transect segments. The sample size represents the number of streams sampled with duplicate samples being collected for each stream. A version of this plot with an enlarged 1998 plot is presented in the Supporting Information as Figure S1. Data to generate the 1998 plot was taken from ref (26).

Silicon tetrachloride (SiCl4) is a byproduct of polysilicon production by an improved Siemens process. (23) It is reported that producing 1 t of polysilicon will generate 10–15 t of SiCl4 byproduct in the improved Siemens process. (24) Additionally, SiCl4 is a highly toxic substance and will immediately decompose into silicate (H2SiO3) and hydrogen chloride (HCl) in wet air, posing a potential threat to human health and the environment. Therefore, the harmless treatment of SiCl4 is necessary and meaningful. Considering the 84% chlorine content of SiCl4, it could possess a strong chlorination effect. Thus, we make an attempt to use SiCl4 as a chlorination agent to recover spent LiCoO2, which simultaneously realizes the harmless treatment and effective recycling of two kinds of waste resources.

It’s official. As of June 19th, I now serve my nation as the Deputy Assistant Secretary for Spent Fuel and Waste Disposition in the Office of Nuclear Energy in the Department of Energy. Due to the concern of negative and threatening responses like we saw in my previous announcement as I was offered the role, including more than a hundred death threats and more vitriol than I could have imagined, I held off announcing my official start until I could be safe and secure in my new role.

But goodness is this a time for celebration! It’s really really official! The beautiful irony that the months-long process of getting me into this role culminated in a Pride month start date is not lost on me. As one of if not the very first openly genderfluid individuals in federal government leadership, I was welcomed with open arms into the Department of Energy all the way up to the Secretary whom I shared the stage with in a Pride month celebration panel just today. To clarify, I am not a Biden appointee (despite what was reported) and instead serve as a career employee in the Senior Executive Service - I intend to be serving my country in this role through many many presidencies.

I’ve prepared for this moment in a technical sense for a decade. Graduating with not one but two degrees from MIT led to working at multiple think tanks where I produced the first-of-a-kind reports and maps on consent-based siting and advanced reactor innovation. Being the first employee of one of the world’s first nuclear waste start-up companies led me to innovate and drive the national conversation of nuclear waste management into the future. And now, I lead a staff of hundreds and a budget of millions (with a Nuclear Waste Fund I’m responsible for at over $45 billion) as the leader of the office overseeing the management of the nation’s spent nuclear fuel.

Thank you for being the community who believed in me. You got me through some dark days these past few months and I’m eternally grateful. Now it's time for me to make my mark as the Deputy Assistant Secretary...

BEQ: WHAT UNIQUE QUALITIES OR PERSPECTIVE DO YOU BRING TO THE FIELD OF NUCLEAR ENERGY AS AN LGBTQ PERSON?
Brinton: THIS is my best argument for my decision to become a nuclear engineer. Think about this: A nuclear engineer is constantly fighting the misperception that they are Homer Simpson and killing the environment with green glowing goo or about to build a nuclear bomb. They are constantly correcting public perception. And that’s what an LGBTQ person is doing too. We are helping our parents realize their idea of who we would marry isn’t necessarily the same. We are showing the world we are more than the stereotypical identities they see on TV. That’s why I think us LGBTQ nuclear engineers are the best nuclear engineers.

Maryna Viazovska, who works on the geometry of spheres, is one of four winners of the coveted prize this year.

Ukrainian number theorist Maryna Viazovska is among the four winners of the 2022 Fields Medals, one of the highest honours in mathematics that is conventionally awarded to people aged under 40. The other winners are James Maynard, a number theorist at the University of Oxford, UK; June Huh, a specialist in combinatorics at Princeton University in New Jersey; and Hugo Duminil-Copin, who studies statistical physics at the Institute of Advanced Scientific Studies (IHES) near Paris. The International Mathematical Union (IMU) announced the winners at an award ceremony in Helsinki on 5 July.

“All of the medalists are incredibly deserving and talented, showcasing the vibrancy of mathematical research across the globe,” says Bryna Kra, a mathematician at Northwestern University in Evanston, Illinois, who is president-elect of the American Mathematical Society.

Viazovska, who is based at the Swiss Federal Institute of Technology in Lausanne (EPFL), is the second woman ever to earn the award. She is best known for her solution of the sphere packing problem — finding the arrangement of spheres that can take up the largest portion of a volume — in eight dimensions.

In a three-dimensional space, the most efficient way to pack spheres is the pyramid arrangement, akin to how oranges are packed on trays in a grocer’s shop (proving this mathematically was extremely hard and was the subject of a tour-de-force paper in the 1990s). But in four or more dimensions, very little is known, says Henry Cohn, a mathematician at the Massachusetts Institute of Technology in Cambridge. “It’s this horrific gap in our knowledge — almost embarrassing,” said Cohn in an address following the Fields Medal announcement. Viazovska introduced new techniques into the problem that came from number theory and the theory of symmetries in eight dimensions. “Given how poor our understanding is in other dimensions, it’s really miraculous that Maryna was able to get this exactly,” Cohn added. More recently, Cohn worked with Viazovska and others to extend the result to 24-dimensional space.

“Viazovska invents fresh and unexpected tools that allow her to jump over natural barriers that have held us back for years,” says Peter Sarnak, a number theorist at Princeton University in New Jersey...

... The Fields Medals and other IMU prizes are normally announced at the opening of the International Congress of Mathematicians (ICM), which takes place every four years. This year’s congress was scheduled to begin on 6 July in St. Petersburg, Russia, but the plan was scrapped following Russia’s invasion of Ukraine in February. Instead, the awards ceremony was moved to Helsinki and the congress will take place as a virtual event.

“We condemn the madness, the injustice, and the irreversibility of war that threatens the very existence of humanity,” wrote four members of what had been the local organizing committee statement on 27 February.

The committee that chooses the Fields winner — whose members’ identities were kept secret until today — reportedly made its decision before the invasion...

Dysprosium (Dy) is considered one of the most critical rare earth elements (REEs). Dy is usually added in neodymium magnets (NdFeB) to improve their heat resistance. (1?4) Due to the high levels of magnetic strength in relative compact sizes, NdFeB magnets have become an indispensable component in several high-tech applications and clean energy technologies, such as industrial robotics, wind turbines, and electric vehicles. (5,6) Demand for Dy has sharply increased since the start of this century. (7) Especially, clean energy technologies are the key to moving toward carbon neutrality, which means that the demand for Dy will further increase in the near future. (8?11) However, the global Dy reserve is limited, leading to concerns on how to achieve sustainable Dy supply. (12,13)

China has the largest REE reserve with an amount of approximate 44 megatons (Mt, 1 Mt = 1,000,000 tons), accounting for 37% of the global reserve in 2019. (14) As for Dy, it is estimated that the global dysprosium oxide (Dy2O3) reserve is 1.62 Mt, referring to 1.41 Mt Dy metallic equivalent. (14) China has the largest Dy reserve with an overall amount of 1.23 Mt, accounting for 87% of the global reserve. (14) Such reserve exists for several common rare earth minerals, such as monazite, xenotime, bastnasite, and ion-adsorbed clays (IACs). In particular, the Dy-rich IACs are distributed only in Southern Chinese provinces, such as Jiangxi, Fujian, Guangdong, and Hunan. However, the accurate flows and stocks of China’s Dy cycle remain unclear.

Material flow analysis (MFA) is one widely recognized method to characterize material flows through the anthroposphere. (15) MFA is capable to track material flows through a specified system boundary and identify how one material transforms and accumulates over its lifecycle based on the principle of mass balance. (16) This method has been employed to analyze most mineral elements and several REEs within different regions and periods, such as aluminum, tungsten, graphite, and neodymium. (17?20) As for the Dy cycle, the existing MFA studies mainly focus on the Dy flows associated with NdFeB in Japan, (1) the impacts of the increasing demand for neodymium (Nd) and Dy on the supply and demand of the host metals and other companion REE in wind power in the US, (12) Dy stocks and flows in NdFeB magnets among 18 various products and its recycling potential by 2035 in Denmark, (21) and the effectiveness of reducing Dy demand from low-Dy NdFeB magnets and promoting NdFeB magnets recycling in Japan for 2010–2030. (22)

Figure 1. MFA framework for China’s Dy cycle.

Based on the principle of mass balance, China’s Dy flows and stocks are classified into five accounting processes from a life cycle perspective.

(1) Domestic flows: domestic flows are the basic Dy flows, covering mining, fabrication, manufacturing, and use stages. They are calculated based on the amounts of primary products, intermediate products, final products, and Dy contents in different products. Various Dy forms are transformed into unique metallic Dy flows. These final products and their Dy contents are listed in Tables S1 and S2.

(2) Trade flows: trade flows reflect the Dy import and export amounts at five stages with various forms. These Dy-containing products are coded by the Harmonized Commodity Description and Coding System of China and listed in Table S3. The trade flows are equal to the traded product amounts multiplied by their corresponding Dy contents.

(3) Loss flows: in this study, the Dy losses are assumed to occur in the R&S stage and fabrication stage, with figures of 10 and 30% respectively. (1,26) These loss flows are calculated by multiplying the production amounts and their loss rates.

(4) Supply-demand flows: Dy flows are calculated by the top-down approach in the R&S stage, while the bottom-up approach is used to estimate the demand for Dy in the fabrication and use stages. Hence, there is a mismatch between the Dy-containing concentrate supply and compound demand, and this gap is considered to be composed of hibernating stock and illegal mining.

(5) In-use stocks: a bottom-up approach is applied to estimate the in-use Dy stocks through the accumulation of net flows since the base year of 2000. (27) The calculation equations are listed as...

Figure 2. Cumulative Dy cycle in China from 2000 to 2019 and the annual Dy cycle in 2009 and 2019. Note: IACs: ion adsorbed clays, MRI: magnetic resonance imaging machines, CV: conventional vehicles, EV: electric vehicles, AC: air conditioners, RE: refrigerators, WM: washing machines, WT: wind turbines, EB: E-bikes, DC: desktop computer, LC: laptop computer, MP: mobile phones, LP: loudspeakers, VC: vacuum cleaners, MO: microwave ovens, EL: elevators, CD: CD/DVD players, IR: industrial robots, and OT: others.

Figure 3. Final Dy demand and application structure in China from 2000 to 2019.

Figure 4. In-use Dy stocks in China from 2000 to 2019.

Figure 5. EoL Dy flows in China from 2000 to 2019.

Figure 6. Historical evolution of Dy supply and demand (a), hibernating stocks (b), illegal mining (c), and price (d) in China from 2000 to 2019.

Figure 7. International Dy trade amounts in China from 2000 to 2019.