The persistent presence of nitrates in the atmosphere has long been a concern for environmental scientists. Despite efforts to reduce emissions over the past few decades, nitrate levels remain stubbornly high. A recent study published in Nature Communications sheds light on this enigma, revealing that chemical processes within the atmosphere are responsible for the persistence of these pollutants.

The research team led by Hokkaido University’s Professor Yoshinori Iizuka examined nitrate deposition history from 1800 to 2020 in an ice core taken from southeastern Greenland. The results showed a gradual increase in nitrates up to the 1970s, followed by a slower decline after the 1990s. This trend mirrors the changes in emissions of nitrate precursors over the same period.

The study’s findings suggest that factors other than emission reductions are driving the persistence of atmospheric nitrates. The researchers used a global chemical transport model to investigate these factors and discovered that atmospheric acidity is the key culprit. As acidity levels rise, more nitrates become trapped in particulate form, enabling them to persist longer and travel farther.

The implications of this study are significant. Accurate measurements of particulate nitrates in ice cores provide valuable data for refining climate modeling predictions. Moreover, the findings suggest that atmospheric nitrates will soon replace sulfates as the primary aerosol in the Arctic, further amplifying warming in the region.

As Professor Iizuka notes, “Ours is the first study to present accurate information for records of particulate nitrates in ice cores.” The persistence of these pollutants highlights the importance of continued research into atmospheric chemistry and climate modeling. By understanding the complex interactions within our atmosphere, we can better predict and prepare for the challenges that lie ahead.

The World Health Organization (WHO) reports that antimicrobial resistance causes more than 1 million deaths every year and contributes to over 35 million additional illnesses. Gram-positive pathogens like Staphylococcus aureus and Enterococcus can cause severe hospital-acquired and community-acquired infections, making the development of effective treatments a pressing concern.

Researchers have recently discovered a synthetic compound called infuzide that shows promise against antimicrobial resistant strains of S. aureus and Enterococcus in laboratory and mouse tests. Infuzide was synthesized as part of a decade-long project by interdisciplinary researchers looking for ways to create compounds that could act against pathogens in ways similar to known pharmaceuticals.

“We started the project as a collaboration, looking for ways to synthesize compounds and connecting them with compounds that might have biological activities,” said medicinal chemist Michel Baltas, Ph.D., from the Laboratoire de Chimie de Coordination at the University of Toulouse in France. Baltas co-led the new work, along with Sidharth Chopra, Ph.D., from the CSIR-Central Drug Research Institute in Lucknow, India.

The researchers found that infuzide specifically attacks bacterial cells and is more effective than the standard antibiotic vancomycin in reducing the size of bacterial colonies in lab tests. In tests of resistant S. aureus infections on the skin of mice, the compound effectively reduced the bacterial population, with an even higher reduction when combined with linezolid.

While infuzide did not show significant activity against gram-negative pathogens, the researchers are exploring small changes to expand its antimicrobial activity. The simplicity of the chemical reactions involved in synthesizing infuzide also makes it easy to scale up production for new treatments.

In addition to its potential against multidrug resistance, the group has been investigating the effects of synthesized compounds on other infectious diseases, including tuberculosis. “We have many other candidates to make antimicrobial compounds,” Baltas said.

The world’s oldest synthetic pigment, Egyptian blue, has been recreated by a team of researchers from Washington State University. This breakthrough, published in the journal NPJ Heritage Science, provides valuable insights for archaeologists and conservation scientists studying ancient Egyptian materials.

Led by John McCloy, director of WSU’s School of Mechanical and Materials Engineering, the research team collaborated with the Carnegie Museum of Natural History and the Smithsonian’s Museum Conservation Institute to develop 12 recipes for the pigment. These recipes utilized a variety of raw materials and heating times, replicating temperatures available to ancient artists.

Egyptian blue was highly valued in ancient times due to its unique properties and versatility. It was used as a substitute for expensive minerals like turquoise or lapis lazuli and applied to wood, stone, and cartonnage – a papier-mâché-type material. Depending on its ingredients and processing time, the pigment’s color ranged from deep blue to dull gray or green.

The researchers’ work aimed to highlight how modern science can reveal hidden stories in ancient Egyptian objects. After the Egyptians, the pigment was used by Romans, but by the Renaissance period, the knowledge of how it was made had largely been forgotten.

In recent years, there has been a resurgence of interest in Egyptian blue due to its intriguing properties and potential new technological applications. The pigment emits light in the near-infrared part of the electromagnetic spectrum, which people can’t see, making it suitable for fingerprinting and counterfeit-proof inks. It also shares similar chemistry with high-temperature superconductors.

To understand the makeup of Egyptian blue, the researchers created 12 different recipes using mixtures of silicon dioxide, copper, calcium, and sodium carbonate. They heated the material at around 1000 degrees Celsius for between one and 11 hours to replicate temperatures available to ancient artists. After cooling the samples at various rates, they studied the pigments using modern microscopy and analysis techniques that had never been used for this type of research.

The researchers found that Egyptian blue is highly heterogeneous, with different people making the pigment and transporting it to final uses elsewhere. Small differences in the process resulted in very different outcomes. In fact, to get the bluest color required only about 50% of the blue-colored components, regardless of the rest of the mixture’s composition.

The samples created are currently on display at Carnegie Museum of Natural History in Pittsburgh, Pennsylvania and will become part of the museum’s new long-term gallery focused on ancient Egypt. This research serves as a prime example of how science can shed light on our human past, revealing hidden stories in ancient objects and materials.