P2X-catalyst needs less Iridium

But new options are already in the pipeline: Within the Kopernikus P2X project, a new efficient iridium-based nanocatalyst was developed by the Heraeus Group, consisting of a thin layer of iridium oxide deposited on a nanostructured titanium dioxide support. The so-called ‘P2X catalyst’ requires only an extremely small amount of iridium, reducing precious metal loading substantially (four times lower than in the current best commercial material).

A team at HZB led by Dr. Raul Garcia-Diez and Prof. Dr.-Ing. Marcus Bär, together with colleagues from the ALBA synchrotron in Barcelona, have studied the P2X catalyst, which shows remarkable stability even in long-term operation, and compared its catalytic and spectroscopic signature with the benchmark commercial crystalline catalyst.

Operando measurements at BESSY II

The HZB team has thoroughly investigated the commercial benchmark catalyst as well as the P2X catalyst at BESSY II during water electrolysis (operando measurements). “We wanted to observe how the two different catalyst materials change structurally and electronically during the electrochemical oxygen evolution reaction using operando Ir L₃-edge X-ray absorption spectroscopy (XAS),” says Marianne van der Merwe, a researcher in Bär’s team. They also developed a new experimental protocol to ensure that the results are measured in both samples under exactly the same oxygen production rate. This made it possible to compare the two catalysts under equivalent conditions.

Different chemical environments explored

“From the measurement data, we were able to conclude that the mechanisms for OER in the two classes of iridium oxide catalysts are different, and this is driven by the different chemical environments of the two materials,” says van der Merwe. The measurement data also show why the P2X catalyst performs even better compared to its more crystalline benchmark: in the P2X sample, the bond lengths between iridium and oxygen decrease significantly more than in the reference catalyst at OER relevant potentials. This reduction in Ir-O bond lengths can be associated to the participation of defective environments that are proposed to be key players in highly active pathways of the oxygen evolution reaction.

“In addition, the electronic state observations also correlate with local geometric information,” van der Merwe points out. “Our work provides valuable key information about the different mechanisms of iridium oxide-based electrocatalysts during the oxygen evolution reaction and deepens our understanding of catalyst performance and stability, while our newly proposed in situ spectroscopic electrochemical protocol approach is generally applicable to all anode materials studied under relevant OER conditions.”

“Tell me why: The missing w in episodic memory’s what, where and when” appears in a special issue of Cognitive, Affective & Behavioral Neuroscience focusing on individual differences in memory modulation. Authors Fernanda Morales-Calva, a graduate student in psychological sciences at Rice, and Stephanie Leal, an adjunct assistant professor of psychological sciences, examined existing research to create a comprehensive analysis of the “three Ws” of memory — what, where and when we remember — to answer the central question of why people remember.

Specifically, the researchers explore how emotional significance, personal relevance and individual differences shape memory retention. Unlike experimental studies, this review gathers and interprets existing findings to advance the understanding of episodic memory.

The review categorizes memory research into three primary domains centered on what, where and when people remember. Morales-Calva and Leal found that memories are often shaped by emotional content, personal significance, repetition and attention. For example, individuals are more likely to remember events with deep emotional resonance or details on which they actively focus.

However, what we remember is also influenced by factors such as where the event happened. What is known as spatial memory is often studied in animals, and the researchers said it is also an important aspect of what we remember that applies to human experiences. New environments command greater attention and therefore foster stronger memories when compared to familiar, routine settings.

Finally, the researchers said when the event occurs makes a difference in what people remember. How individuals sequence events and recognize transitions between them plays a critical role in memories. Specific events are often compartmentalized into distinct episodes and therefore can be easier for individuals to recall.

In addition to the what, where and when of memory, Morales-Calva said individual circumstances, including cultural, personal and cognitive differences, can have a significant impact in shaping how individuals remember.

“Memory is not a one-size-fits-all phenomenon,” Morales-Calva said. “What’s memorable for one person might be entirely forgettable for another depending on their unique background and cognitive priorities.”

The researchers said that examining why we remember certain experiences over others can have significant implications for both clinical and everyday settings. For instance, professional memory assessments often rely on standardized tests developed in specific cultural contexts, which have the potential to overlook critical individual differences, the researchers said. Such tests may yield skewed results when applied in diverse populations, highlighting the need for more tailored approaches.

As the global population ages and memory impairments become increasingly prevalent, understanding the specific factors that shape memory could inform interventions for conditions like dementia and cognitive decline, the researchers said.

“This review highlights the importance of considering subjectivity and context in memory research,” Leal said. “By accounting for these variables, we can develop more accurate diagnostic tools and effective interventions.”

The authors argue that complexity of memory can be better understood when the researchers incorporate individual differences into experimental designs. By doing so, they say they hope to bridge gaps between laboratory findings and real-world applications to foster a deeper understanding of the human experience.

The findings, which have been published in the journal Parasitology, present some of the earliest evidenceof schistosomiasis outside its endemic region of Africa.

“Many of the parasites we see today have been around for centuries. One of our goals in infectious disease studies is to understand where in the world people had these parasites in the past and how their epidemiology has changed through time,” says Marissa Ledger, a post-doctoral fellow at McMaster’s Ancient DNA Centre, who led the research.

Schistosomiasis is caused by Schistosoma mansoni, a water-borne parasitic flatworm that can burrow into the skin, move through the bloodstream and establish itself in the intestines. There it reproduces and releases eggs, which are passed through human waste. Ledger discovered a preserved egg in the contents of a 15^th-century latrine in present-day Belgium, thousands of kilometers away from its endemic region.

The latrine had been uncovered in an excavation in 1996, but its artifacts and organic remains were only recently examined as part of a larger research project at Ghent University focused on the many foreign communities living and trading in medieval Bruges and its former harbor towns.

Researchers say the latrine came from a house known as the Spanish nation house, the administrative seat and meeting place of the Castilian merchant community. The parasite in question is likely associated with one of these Spanish traders who facilitated the import of African commodities like gold dust, ivory and various spices. There’s also evidence they were involved in the early Atlantic slave trade.

The combination of this rich historical record with the archaeological and parasitological data is quite unique and helps us better understand human migration and disease transmission in the past and underscores the historical significance of this Belgian-Canadian collaboration.

“Our findings speak to the complexity of medieval urban life and how interconnected this world was centuries ago. It not only provides novel insight into daily life of people in medieval Bruges but also shows how the city, known as an international hub for people, goods and ideas, inevitably also facilitated the spread of diseases through its strong maritime trade networks,” says Maxime Poulain, archaeologist at Ghent University.

It also demonstrates the importance of analyzing organic remains from these types of archaeological finding, as it can provide information on the health, hygiene and mobility of populations.

Ledger plans to analyze the genetics of the parasite to understand how its makeup compares to that of its modern counterparts.

“Understanding these parasites over a broader time frame provides more information on how they are impacted by factors like migration. Even in the past as people were migrating over these long distances, they were still very effectively moving infectious diseases across long distances. That’s incredibly useful to know.”

The CAST/EiJ mouse, part of a research panel including eight genetically diverse mouse strains, stands out for its severe response to SARS-CoV-2 infection, including beta, omicron, and delta variants. While other strains either recovered or showed mild symptoms, the CAST mice displayed acute illness, highlighting their unique susceptibility to the virus.

“Although most mice strains have negligible symptoms from infection with SARS-CoV-2 variants, CAST mice exhibit a lethal response, making them an invaluable resource for studying the virus’s impact and testing next-generation therapies,” said Nadia Rosenthal, scientific director and professor at JAX, and one of the senior authors of the study.

Originally collected on the island of Castania and brought to JAX in 1971, CAST mice were bred at JAX to maintain a genetically pure line, creating a model as true to the mouse genome as possible. This characteristic makes them an ideal model for investigating severe COVID-19 symptoms on a clean genetic background.

These mice not only carry high viral loads in the lungs but also display severe lung damage, mirroring the kind of hyperinflammatory response seen in human patients with severe COVID-19. This unique strain offers researchers a model that closely parallels the human response to the virus without brain infection — an issue in previous models of COVID-19.

Initial trials using antiviral treatments have shown promising results, boosting survival rates in CAST mice and sparking hope for their role in developing therapies for future coronavirus outbreaks. As new variants continue to emerge, the CAST mouse model stands ready to accelerate a response, providing insights that could ultimately save lives.

Diversity in mouse models offers new perspectives

The study explored eight genetically diverse mouse strains, including A/J, B6J, CAST, 129S1, NSG, NZO, PWK, and WSB, encompassing traits like type 1 and type 2 diabetes susceptibility, obesity, and leanness. These diverse genetic backgrounds enabled the team to uncover differences in virus susceptibility.

Rosenthal and Candice Baker, director of research projects at JAX and first author of the study, started with all eight strains of mice and found the CAST mouse stood out as a highly susceptible mouse for Sars-CoV-2 infection. While the CAST mice didn’t recover, some strains did but displayed lingering symptoms resembling long-COVID.

“The CAST mice gave us insight into the acute symptoms of COVID-19, but now we are going to look at the long-term effects,” said Baker.

In follow-up work, Rosenthal and Baker plan to investigate long-term impacts using this same panel of eight mice.

Overcoming the early challenges of COVID-19 research

When the pandemic began, traditional mouse models were unsuitable for SARS-CoV-2 research, as their cells lack the receptors needed for the virus to bind. In 2023, Rosenthal and her team at JAX and NIH’s Rocky Mountain Laboratories addressed this by using mice engineered with human versions of these receptors, but the resulting infections were overly severe and failed to mimic the spectrum of human responses.

By crossing genetically engineered mice with diverse strains, Rosenthal’s team replicated a range of human-like responses. But these engineered human receptors don’t always give a clinically relevant disease phenotype. The CAST mouse is invaluable, as its genetic background avoids artificial receptor modifications, making it a more natural model for studying severe COVID-19.

“CAST mice stand poised to transform COVID-19 research and prepare us for future challenges,” said Rosenthal. “Equally important, the work reinforces the critical role of genetic diversity in science.”