In a groundbreaking study published in Physical Review Letters, Professor Dong Eon Kim from POSTECH’s Department of Physics and his research team have successfully unraveled the mystery of electron tunneling, a fundamental concept in quantum mechanics. This achievement marks a significant milestone in understanding one of the most enduring enigmas in physics – a phenomenon that has puzzled scientists for over 100 years.

Quantum tunneling is a process where electrons pass through energy barriers (or “walls”) that they seemingly cannot surmount with their energy, much like digging a tunnel through them. This phenomenon underlies the operation of semiconductors, which power smartphones and computers, as well as nuclear fusion – the process that generates light and energy in the sun.

Until now, while some understanding existed about what happens before and after an electron passes through a tunnel, the exact behavior of the electron as it traverses the barrier remained unclear. Enter Professor Kim’s team, who collaborated with researchers from the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, to conduct an experiment using intense laser pulses to induce electron tunneling in atoms.

The results revealed a surprising phenomenon: electrons do not simply pass through the barrier but collide again with the atomic nucleus inside the tunnel. This process was dubbed “under-the-barrier recollision” (UBR) by the research team. Until now, it was believed that electrons could only interact with the nucleus after exiting the tunnel, making this a groundbreaking discovery.

Moreover, during UBR, electrons gain energy inside the barrier and collide again with the nucleus, strengthening what is known as “Freeman resonance.” This ionization process was significantly greater than previously observed and remained largely unaffected by changes in laser intensity – a completely new finding that defied existing theories.

This research marks a crucial step forward in understanding quantum tunneling dynamics. As such, it has significant implications for the development of advanced technologies like semiconductors, quantum computers, and ultrafast lasers, which rely on precise control over electron behavior and increased efficiency.

Professor Kim emphasizes, “Through this study, we’ve found clues about how electrons behave when they pass through the atomic wall.” He concludes, “Now, we can finally understand tunneling more deeply and control it as we wish.”

This research received support from the National Research Foundation of Korea and the Capacity Development Project of the Korea Institute for Advancement of Technology.

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.

With the world’s population growing at an unprecedented rate, urban expansion has reached new heights, putting immense pressure on natural resources and the environment. The construction industry, in particular, is facing significant challenges in reducing its carbon footprint while meeting the demand for infrastructure development.

Ordinary Portland Cement (OPC) remains a cornerstone of modern-day infrastructure, despite being a major contributor to global carbon emissions. To address this issue, scientists from Japan have developed a game-changing solution: a high-performance geopolymer-based soil solidifier made from Siding Cut Powder (SCP), a construction waste byproduct, and Earth Silica (ES), sourced from recycled glass.

This breakthrough innovation offers an alternative to reducing cement dependence while transforming construction waste into valuable construction resources. The combination of SCP and ES forms a geopolymer-based solidifier capable of enhancing soil-compressive strength beyond construction-grade thresholds of 160 kN/m2.

The thermal treatment process, which involves heating SCP at 110 °C and 200 °C, significantly improves its reactivity and reduces material use without sacrificing performance. This solution not only meets industry standards but also helps address the dual challenges of construction waste and carbon emissions.

A noteworthy aspect of this research is the approach to environmental safety. Initially, concerns were raised regarding arsenic leaching from recycled glass content in ES. However, scientists demonstrated that incorporating calcium hydroxide effectively mitigated this issue through the formation of stable calcium arsenate compounds, ensuring full environmental compliance.

The implications of this solution are vast and far-reaching. In urban infrastructure development, it can stabilize weak soils beneath roads, buildings, and bridges without relying on carbon-intensive Portland cement. This is particularly valuable in areas with problematic clay soils where conventional stabilization methods are costly and environmentally burdensome.

Disaster-prone regions could benefit from rapid soil stabilization using these materials, which have demonstrated good workability and setting times compatible with emergency response needs. Additionally, rural infrastructure projects in developing regions could utilize these materials to create stabilized soil blocks for construction, providing a low-carbon alternative to fired bricks or concrete.

The geopolymer solidifier offers numerous practical applications across industries. For the construction sector, which faces increasing pressure to decarbonize, this solution provides an alternative that exceeds traditional methods without heavy carbon footprints. For geotechnical engineering firms, its proven durability under sulfate attack, chloride ingress, and freeze-thaw cycles allow its use in demanding and aggressive environments.

By lowering Portland cement usage, this technology supports construction projects aiming to meet green building certifications and carbon reduction targets. It may also allow developers to qualify for environmental incentives in countries where carbon pricing mechanisms are in place, further enhancing its economic viability.

The vision behind this work is broader than just developing a sustainable engineering solution – it’s redefining how we value industrial byproducts in a resource-constrained world. These findings point to a transformative shift in sustainable construction practices, potentially transforming millions of tons of construction waste into valuable resources while reducing the carbon footprint associated with cement production.