The study, published in the May issue of the journal Environmental Pollution, examined contamination levels for Mercury, Zinc, Cadmium and Antimony from nearly 50 sites in the Rocky Mountains. DRI’s Monica Arienzo, Associate Research Professor of Hydrology, led the research, along with colleagues from the U.S. Geological Survey (USGS), the University of Nevada, Reno, and Portland State University. They found higher levels of metal contaminants in the northern Rockies and identified mines in the Pacific Northwest, Idaho, and Montana as the likely source by following winter storms back in time. It is one of the first studies to look at metal contamination across the greater Rocky Mountains.

“Metal pollution in the Rockies is relatively understudied,” Arienzo said. “Other studies have focused on certain parts, so the fact that we have this transect from Montana to New Mexico makes this study unique.”

Although contamination levels were found to be within guidelines set by the EPA for both drinking water and aquatic life, dust can accelerate snowmelt by decreasing the reflectivity of the snowpack. The data can also provide critical information about how environmental contaminants and dust are distributed by the atmosphere.

The study combined a number of data sets to capture a comprehensive understanding of the amount of metal contamination making its way to the region. First, snow samples were collected from 48 sites throughout the Rocky Mountains during the spring of 2018. The researchers then measured metal concentrations in each sample, including metals like calcium that come from natural dust rather than human activities. By comparing the amounts of purely dust-sourced metals to those that result from both dust and industrial activities like mining, the scientists determined how much metal contamination stemmed from human activities.

To strengthen their findings, they then examined data from the National Atmospheric Deposition Program that measured mercury and calcium in precipitation from 2009 through 2018. Again, the scientists saw higher amounts of metal contamination in the northern Rockies, across Montana, Idaho, and Northern Wyoming.

“I was surprised by the amount of agreement we saw between all these different data sets we brought together,” Arienzo said. “The snow samples showed us that contamination is higher in the northern Rockies, and that was really interesting. Looking at mercury contamination over time helped us say that 2018 is not just a fluke. When you start to see these trends that are consistent between different records, it makes you feel more confident that something’s really happening here.”

To determine the likely source of the contaminants, Arienzo and her colleagues tracked the winter’s storms back through time. For the northern Rockies, many of the storms had moved in from the Pacific Northwest region, whereas in the southern stretch of the mountains, storms came from across the Mojave Desert.

By referencing a USGS dataset that tracks mining and smelting locations, the scientists identified active sites near the northern Rockies. An examination of EPA Superfund locations uncovered historical sites that could also be sources of contamination.

“Our idea is that the dust from current and historical mining sites gets carried up into the mountains and deposited across our study sites,” Arienzo said. “This study shows the importance of continued scientific monitoring efforts, like the long-term USGS datasets we used here, as well as mitigation of current and historical mining sites.”

The research is part of a larger study, supported by the National Science Foundation (NSF), using tree rings to examine historical mercury contamination. Arienzo and her team will compare the mercury record found in tree rings to that found in the snowpack to better understand how mercury is deposited and spread throughout the environment.

Now, findings from researchers at Texas A&M University provide new, evidence-based insight into minimizing the risk of these diseases at canine facilities.

“In adult, healthy humans and animals, these diseases usually cause diarrhea and occasionally other minor ailments, but for infants, puppies and the immunocompromised, infection could be deadly,” said Loni Taylor, PhD, DVM, an epidemiologist with the Texas A&M University School of Public Health, who led the study. “We wanted to identify the factors associated with kennel-housed dogs in Texas that test positive for both diseases.”

For their study, published in Comparative Medicine, Taylor and five colleagues with Texas A&M’s College of Veterinary Medicine & Biomedical Sciences sought to find out if a dog’s score on the Purina Fecal Scoring chart, breed, sex or age was associated with testing positive on a fecal screening test for either Giardia, Cryptosporidium or both organisms together.

To accomplish this, they tested fecal samples collected from a census sample of 153 clinically normal dogs housed at Texas kennels between March and October 2021. Breeds included golden retrievers, Labrador retrievers, beagles and a variety of large hounds and hound mixes.

The sex, age, breed and location were noted for the 153 dogs studied. In addition, fecal scores were determined by a single researcher using visual assessment of the samples, based on the Purina Institute metric (where 1 is hard and 7 is watery).

A secondary data analysis and statistical analysis found that dogs were significantly more likely to test positive for Giardia (45%) than Cryptosporidium (7%) (P < 0.01), although no clear link was found between sex or breed and these infections.

In addition, kennel-housed dogs 18 months of age or younger had 3.4 times the odds of Giardia infection compared with older dogs, and hard stool was associated with negative test status for Giardia in the stool.

No statistically significant relationship was found for age or fecal score and Cryptosporidium-positive test status, and Taylor noted that additional studies with larger sample sizes could help identify such a relationship.

“The primary takeaway is that age and fecal score are important factors for choosing which dogs to screen for subclinical Giardia,” Taylor said. “And given the increased odds of Giardia infection, screening should be as robust as the recommended combination of testing methods.”

Now, researchers in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) are doubling down, literally, on metasurface technology by creating a bilayer metasurface, made of not one, but two stacked layers of titanium dioxide nanostructures. Under a microscope, the new device looks like a dense array of stepped skyscrapers.

The research is published in Nature Communications.

“This is a feat of nanotechnology at the highest level,” said senior author Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. “It opens up a new way to structure light, in which we can engineer all its aspects such as wavelength, phase and polarization in an unprecedented manner…It signifies a new avenue for metasurfaces that so far has been just scratching the surface.”

For centuries, optical systems have relied on bulky, curved lenses made of glass or plastic to bend and focus light. The SEAS-led metasurface revolution of the last decade has produced flat, ultra-thin structures patterned with millions of tiny elements that can manipulate light with nanometer precision. A striking example technology is the metalens: Unlike conventional lenses, metalenses can be fabricated with existing semiconductor manufacturing, making possible compact, integrated optical systems in devices like smartphones, cameras, and augmented reality displays.

After Capasso’s team reported their first working metalens that can bend visible light, they worked with Harvard’s Office of Technology Development to license the technology and start a company, Metalenz. They’ve since demonstrated a host of potential applications, including an endoscope, an artificial eye, and a telescope lens.

But the single-layer nanostructure design Capasso’s team invented has been in some ways limiting. For example, previous metasurfaces put specific requirements on the manipulation of light’s polarization — that is, the orientation of the light waves — in order to control the light’s behavior.

“Many people had investigated the theoretical possibility of a bilayer metasurface, but the real bottleneck was the fabrication,” said Alfonso Palmieri, graduate student and co-lead author of the study. With this breakthrough, Palmieri explained, one could imagine new kinds of multifunctional optical devices — for example, a system that projects one image from one side and a completely different image from the other.

Using the facilities of the Center for Nanoscale Systems at Harvard, the team that included former postdoctoral researchers Ahmed Dorrah and Joon-Suh Park came up with a fabrication process for freestanding, sturdy structures of two metasurfaces that hold strongly together but do not affect each other chemically. While such multi-level patterning has been common in the silicon semiconductor world, it had not been as well explored in optics and metaoptics.

To demonstrate the power of their device, the team devised an experiment in which they used their bilayer metalens to act on polarized light in the same way that a complicated system of waveplates and mirrors does.

In future experiments, the team could expand into even more layers to exert control over other aspects of light, such as extreme broadband operation with high efficiency across the entire visible and near infrared spectrum, opening the door to even more sophisticated light-based functionalities.

The research was supported by several federal funding sources, including the Office of Naval Research under grant No. N00014-20-1-2450, and from the Air Force Office of Scientific Research under grant No.s FA9550-21-1-0312 and FA9550-22-1-0243. The devices were made at the Harvard University Center for Nanoscale Systems, part of the National Nanotechnology Coordinated Infrastructure Network, which is supported by the National Science Foundation under NSF award No. ECCS-2025158.

Staff acknowledgments: Stephan Kraemer supported the focused ion beam process, and Mac Hathaway supported the atomic layer deposition process.