Tag: Japan

Dendritic structures that emerge during the growth of thin films are a major obstacle in large-area fabrication, a key step towards commercialization. However, current methods of studying dendrites involve crude visual inspection and subjective analysis. Moreover, growth optimization methods for controlling dendrite formation require extensive trial and error. Now, researchers have developed a new AI model that incorporates topology analysis and free energy to reveal the specific conditions and mechanisms that drive dendrite branching.

Thin film devices, composed of layers of materials a few nanometers thick, play an important role in various technologies, from semiconductors to communication technologies. For instance, graphene and hexagonal-boron nitride (h-BN) multilayer thin films, deposited on copper substrates, are promising materials for next-generation high-speed communications systems. Thin films are grown by depositing tiny layers of materials onto a substrate. The growth process conditions significantly influence the microstructure of these films, which in turn influences their function and performance.

Dendritic structures, or tree-like branching patterns that emerge during growth, pose a major challenge to large-area fabrication of thin-film devices, a key step toward commercial application. They are commonly observed in materials like copper, graphene, and borophene, particularly in the early growth stage and multilayer films. Since the microstructure directly impacts device performance, reducing dendritic formation is, therefore, critical. However, methods for studying dendrites have largely relied on crude visual analysis and subjective interpretation. Understanding the conditions that drive dendritic branching is essential for optimizing the thin-film growth process, but existing approaches often require considerable trial and error.

To address these challenges, a research team, led by Professor Masato Kotsugi from the Department of Material Science and Technology at Tokyo University of Science (TUS), Japan, developed an innovative explainable artificial intelligence (AI) model for analyzing dendritic structures. The team included Misato Tone, also from TUS, and Ippei Obayashi from Okayama University. The team developed a novel method that bridges structure and process in dendritic growth by integrating persistent homology and machine learning with energy analysis. “Our approach provides new insights into growth mechanisms and offers a powerful, data-driven pathway for optimizing thin-film fabrication,” explains Prof. Kotsugi. Their study was published online in Science and Technology of Advanced Materials: Methods on March 7, 2025.

To analyze the morphology of dendrite structures, the team used a cutting-edge topology method called persistent homology (PH). PH enables multiscale analysis of holes and connections within geometric structures, capturing the complex topological features of the tree-like dendrite microstructures that conventional image processing techniques often overlook.

The researchers combined PH with principal component analysis (PCA), a machine learning technique. Through PCA, the essential features of the dendrite morphology extracted via PH were reduced to a two-dimensional space. This enabled the team to quantify structural changes in dendrites and establish a relationship between these changes and Gibbs free energy, or the energy available in a material that influences how dendrites form during crystal growth. By analyzing this relationship, they uncovered the specific conditions and hidden growth mechanisms that influence dendritic branching. Prof. Kotsugi explains, “Our framework quantitatively maps dendritic morphology to Gibbs free energy variations, revealing energy gradients that drive branching behavior.”

To validate their approach, the researchers studied dendrite growth in a hexagonal copper substrate and compared their results with data from phase-field simulations.

“By integrating topology and free energy, our method offers a versatile approach to material analysis. Through this integration, we can establish a hierarchical connection between atomic-scale microstructures and macroscopic functionalities across a wide range of materials, paving the way for future advancements in material science,” remarks Prof. Kotsugi. “Importantly, our method could lead to the development of high-quality thin-film devices leading to high-speed communication beyond 5G.”

This study’s framework could pave the way for breakthroughs in sensor technology, nonequilibrium physics, and high-performance materials by uncovering hidden structure-function relationships and advancing complex system analysis.

Overuse of chemical pesticides has driven resistance in agricultural pests, including the adaptable two-spotted spider mite. Researchers from Japan have discovered novel elicitor proteins, Tet3 and Tet4, in mite saliva that could enhance sustainable pest control. They found that these proteins play a crucial role in modulating plant defense responses by acting as key players in the complex interactions between parasite and host, paving the way for new mite countermeasures.

As global food demand continues to increase, effective pest control remains one of agriculture’s most pressing challenges. Worldwide, farmers apply nearly 4 million tons of chemical pesticides annually to protect their crops, representing a $60 billion industry. While these compounds have significantly boosted agricultural productivity, their widespread use has raised concerns regarding environmental impact, health risks, and the long-term sustainability of modern farming.

The two-spotted spider mite, Tetranychus urticae, exemplifies the limitations of conventional pesticide-based pest management in agriculture and horticulture. These microscopic arachnids infest a wide range of crops and fruit trees and can reproduce extremely quickly. More importantly, unlike many other pests, they rapidly develop resistance to chemical pesticides, making control efforts increasingly challenging. With pesticide resistance on the rise, farmers worldwide are urgently seeking alternative, sustainable pest control strategies.

A research team led by Professor Gen-ichiro Arimura from the Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Japan, closely examined the fine molecular interplay that occurs between T. urticae mites and their host plants. Their study was published online in The Plant Journal on March 4, 2025. The team focused on specific substances called elicitors, secreted by T. urticae, and examined their biological effects on various crops.

“An elicitor is a molecule that plants or pests possess that can enhance the defense response of plants,” explains Prof. Arimura. “In our previous research, we identified two tetranins, labeled Tet1 and Tet2, as elicitors in the salivary glands of two-spotted spider mites; these substances induce defense responses in the common bean and other commercially important crops.”

The research team investigated the effects of an additional 18 salivary gland proteins on the resistance of common bean leaves to T. urticae. According to this initial screening, they identified two new tetranins—Tet3 and Tet4—that appear to reduce the reproduction of spider mites on the plants.

After a series of experiments involving genetic engineering and advanced molecular and biochemical methods, the team uncovered the roles of Tet3 and Tet4 in the complex interactions between T. urticae and its host plants. Interestingly, they found that the expression of Tet3 and Tet4 varies greatly depending on which plant the mites fed on. Mites feeding on common beans, their preferred host, had significantly higher levels of Tet3 and Tet4 expression than those on cucumbers, a less preferred option.

Notably, plants exposed to mites with higher expression of Tet3 and Tet4 exhibited stronger defense responses, including increased calcium-ion influx, higher generation of reactive oxygen species, and elevated expression of a defensive gene named PR1. The individual application of Tet3 and Tet4 to plants had different effects on plant defense responses, highlighting the specificity of each elicitor’s role. “Taken together, our findings show that these tetranins respond to variable host cues that may optimize herbivore fitness by altering the anti-mite response of the host plant,” remarks Prof. Arimura.

The implications of these findings are twofold. First, understanding the molecular mechanisms that underlie interactions between organisms leads to a better understanding of evolution, ecosystems, and biodiversity. Elicitors such as tetranins act as crucial links in these complex systems, making their detailed study essential for uncovering broader biological insights. From an agricultural perspective, tetranins and similar elicitors offer potential for crop improvement, as insights into the elicitor-sensing system can aid in breeding more sensitive and resilient crops. “Elicitors may be useful as biostimulants that can increase the potential pest resistance of plants,” highlights Prof. Arimura. “The development of such organic farming techniques is extremely meaningful in today’s world, as the environmental and ecological impact of heavy pesticide use grows more severe. Hopefully, identifying elicitors secreted by pests and elucidating their functions will lead to unprecedented spider mite countermeasures.”

With continued research, this fascinating topic could contribute to more sustainable agriculture and enhanced food safety.

Irritable bowel syndrome (IBS) is a common digestive disorder with unclear causes, affecting about 10% of the global population. Researchers from Japan have now discovered that opioid delta-receptor agonists may alleviate IBS symptoms by acting directly on the central nervous system. Using a novel stress-induced mouse model, they found these drugs reduce abdominal pain and regulate bowel movements. This research suggests a promising approach to treating IBS by targeting stress as a contributing factor.

Irritable bowel syndrome (IBS) is a common digestive disorder that affects the intestine, causing symptoms such as abdominal pain, bloating, gas, and changes in bowel habits, including diarrhea, constipation, or both. Although this condition affects about a tenth of the global population, the underlying causes and mechanisms of IBS remain unclear. Consequently, treatments for IBS primarily focus on managing symptoms rather than addressing the root cause of the disorder.

At Tokyo University of Science (TUS), Japan, Professor Akiyoshi Saitoh and his research group have spent the past decade exploring this topic. This study published online in the British Journal of Pharmacology on December 25, 2024, discovered that a class of drugs called opioid delta-receptor (DOP) agonists may help alleviate IBS symptoms by targeting the central nervous system rather than acting directly on the intestine. This study was co-authored by Toshinori Yoshioka, a third-year PhD student at TUS.

One of the main motivations for this study was the growing evidence linking IBS closely to psychological stress. Saitoh’s group aimed to address this potential root cause by focusing on finding a novel animal model for this condition. In a study published in 2022, they developed a mice model repeatedly exposed to psychological stress—using a method called chronic vicarious social defeat stress (cVSDS)—which developed symptoms similar to a type of IBS called IBS-D. These symptoms included overly active intestines and heightened sensitivity to abdominal pain, even though their organs showed no physical damage. The cVSDS animal model involved having the subject mouse repeatedly witness a territorial, aggressive mouse defeating a cage mate, inducing indirect chronic stress.

Using the cVSDS model, the researchers sought to determine whether DOP in the brain, which is closely linked to pain and mood regulation, could serve as promising drug targets for treating stress-induced IBS. To achieve this, they performed a series of detailed experiments to observe the effects of DOP agonists on IBS symptoms and chemical signaling in the brain. Some experiments involved measuring the speed of a charcoal meal through the intestine to assess gastrointestinal motility and evaluate the impact of stress or treatments on bowel movement speed, along with directly measuring neurotransmitter concentrations using in vivo brain microdialysis. This revealed that re-exposure to VSDS increased glutamate levels in the insular cortex, but these elevated levels were normalized with DOP agonists.

According to the results, the administration of DOP agonists helped relieve abdominal pain and regulated bowel movements in cVSDS mice. Interestingly, applying the DOP agonists directly to a specific brain region called the insular cortex had similar effects on IBS symptoms as systemic treatment. “Our findings demonstrated that DOP agonists acted directly on the central nervous system to improve diarrhea-predominant IBS symptoms in mice, and suggest that the mechanism of action involves the regulation of glutamate neurotransmission in the insular cortex,” highlights Saitoh.

Taken together, the continued research by Saitoh’s group on this topic could pave the way for effective treatments for IBS. “DOP agonists could represent a groundbreaking new IBS treatment that not only improves IBS-like symptoms but also provides anti-stress and emotional regulation effects. In the future, we would like to conduct clinical developments with the goal of expanding the indication of DOP agonists for IBS, in addition to depression,” remarks Saitoh.

Compared to currently available IBS treatments, such as laxatives, antidiarrheals, analgesics, and antispasmodics, targeting the underlying stress with DOP agonists may offer a more definitive solution with minimal adverse effects. Further clarification of the roles of stress and brain chemistry in the development of IBS will be essential in achieving this much-needed medical breakthrough. With promising prospects, future studies will translate Saitoh’s group’s findings to humans, bringing great relief to those affected by IBS.