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Category: engineering

InN thin films show transient Pauli blocking for broadband ultrafast optical switching

Recent decades have witnessed rapid advancements in high-intensity laser technology. The combination of laser irradiation and novel materials is opening exciting avenues for the design of functional materials and devices. Semiconductors are ideal platforms for generating laser-driven functionalities because they can exhibit novel features such as ultrafast optical transparency. This effect arises from electronic occupation redistribution driven by ultrafast excitation, which manifests as a phenomenon called transient Pauli blocking.

In a new development, a team of researchers in Japan, led by Professor Junjun Jia from the Global Center for Science and Engineering and the Graduate School of Advanced Science and Engineering at Waseda University, has examined the transient Pauli blocking effect in an InN film.

The study utilized pump-probe transient transmittance measurements with multicolor probe lasers, alongside first-principles electronic band-structure calculations. Their findings are published in Physical Review B.

New technique spots hidden defects to boost reliability of ultrathin electronics

Future devices will continue to probe the frontier of the very small, and at scales where functionality depends on mere atoms, even the tiniest flaw matters. Researchers at Rice University have shown that hard-to-spot defects in a widely used two-dimensional insulator can trap electrical charges and locally weaken the material, making it more likely to fail at lower voltages. The findings are published in Nano Letters.

“By showing practical ways to detect when and where these defects form, we help make future devices more reliable and repeatable,” said Hae Yeon Lee, an assistant professor of materials science and nanoengineering at Rice, who is a corresponding author on the study.

Building ultrathin electronics such as advanced transistors, photodetectors and quantum devices involves stacking sheets of different 2D materials on top of each other into “heterostructures.” Hexagonal boron nitride (hBN), prized for being atomically flat and chemically stable, is a common building block.

Hair-width LEDs could eventually replace lasers

LEDs no wider than a human hair could soon take on work traditionally handled by lasers, from moving data inside server racks to powering next-generation displays. New research co-authored by UC Santa Barbara doctoral student Roark Chao points to a practical path forward. The study is published in the journal Optics Express.

“We’re talking about devices that are literally the size of a hair follicle,” said Chao, who studies electrical engineering. “If you can engineer how the light comes out, those microLEDs can start to replace lasers in short-distance data communication.”

The work builds on UCSB’s longstanding strengths in gallium nitride research and optoelectronics. Chao is co-advised by Steven P. DenBaars and Jon A. Schuller, both co-authors on the study, which also includes Nobel laureate Shuji Nakamura, whose pioneering work on blue LEDs transformed global lighting and display technologies. The research was conducted in the laboratories of the DenBaars/Nakamura and Schuller groups, where teams focus on gallium nitride materials growth and nanoscale photonics.

System isolates single extracellular vesicle surface proteins to map function

Extracellular vesicles (EVs) are tiny biological bubbles that carry nucleic acids and proteins between cells, playing an essential role in tissue repair, neuroprotection and immune health. By isolating the surface proteins of these bubbles, researchers can understand more about their biology and build tools to transform extracellular vesicles into next-generation drugs for cancer, neurological conditions and other diseases.

UC Davis biomedical engineers are using EVs to crack the code of the body’s message system. Their findings are detailed in a paper published in ACS Nano.

“EV-mediated intercellular communication is a very powerful system that controls many physiological and pathophysiological phenomena,” said Aijun Wang, a corresponding author of the new study. Wang is Chancellor’s Fellow and professor of biomedical engineering and surgery. “We know that EVs are therapeutically useful. But how do we define what dictates their functions?”

Ultra-efficient optical sensors can keep light circulating longer inside a microscopic chip

CU Boulder researchers have built high-performing optical microresonators, opening the door for new sensor technologies. At its simplest form, a microresonator is a tiny device that can trap light and build up its intensity. Once the intensity is high enough, researchers can perform unique light operations.

“Our work is about using less optical power with these resonators for future uses,” said Bright Lu, a fourth-year doctoral student in electrical and computer engineering and a lead author on the study. “One day these microresonators can be adapted for a wide range of sensors from navigation to identifying chemicals.”

For this endeavor, published in Applied Physics Letters, the team focused on “racetrack” resonators, named for their elongated shape that resembles a running track.

Core–Shell Engineering of One-Dimensional Cadmium Sulfide for Solar Energy Conversion

Fabricating efficient photocatalysts that can be used in solar-to-fuel conversion and to enhance the photochemical reaction rate is essential to the current energy crisis and climate changes due to the excessive usage of nonrenewable fossil fuels.

Eyes may be a window into early Alzheimer’s detection

The eyes—specifically, the outer area of the retina—may provide a window into early detection of Alzheimer’s disease (AD) long before irreversible brain damage has occurred, according to new research from Houston Methodist. This discovery could dramatically change how the disease is diagnosed, monitored and treated.

“Retinal Müller glia alterations and their impact on ocular glymphatic clearance in an Alzheimer’s disease mouse model,” is online and will appear in an upcoming edition of the Journal of Alzheimer’s Disease. Led by Stephen Wong, Ph.D., the John S. Dunn Presidential Distinguished Chair in Biomedical Engineering at Houston Methodist and director of T. T. & W. F. Chao Center for BRAIN, the study reveals how the peripheral retina (versus the central retina) could be a window into early diagnosis of AD.

“The eyes are indeed a window into the brain, but our study reveals that we have been looking at the wrong part of the window,” Wong said. “While most clinical eye exams focus on the central retina, the most critical early indicators of AD appear to be hidden at the periphery of the eye. By identifying these retinal changes that occur before the brain’s ‘plumbing’ system fails, doctors may eventually be able to use routine eye exams to catch and treat the disease years before memory loss begins.”

Scientists Grew Mini Brains, Then Trained Them to Solve an Engineering Problem

A few blobs of lab-grown brain tissue have demonstrated a striking proof of concept: living neural circuits can be nudged toward solving a classic control problem through carefully structured feedback.

In a closed-loop system that delivered electrical feedback based on performance, cortical organoids could steadily improve their control of a classic engineering benchmark: balancing an unstable virtual pole.

The improvement is far from a functioning hybrid biocomputer. But as a proof of concept, it shows that neural tissue in a dish can be adaptively tuned through structured feedback – a result that could help researchers probe how neurological disease alters the brain’s capacity for plasticity.

Engineered nanoparticles could deliver better targeted cancer treatment to lymph nodes

Scientists at McGill University and the Rosalind and Morris Goodman Cancer Institute have developed a new way to deliver cancer immunotherapy that caused fewer side effects compared to standard treatment in a preclinical study. The work is published in the journal Proceedings of the National Academy of Sciences.

The experimental approach is designed to treat cancer that has spread to the lymph nodes, a difficult-to-treat stage of the disease. Today, most immunotherapies are delivered by intravenous (IV) infusion and circulate throughout the body. This can trigger immune responses in healthy tissues, leading to serious side effects.

“Some immunotherapies cause such severe side effects that clinicians are forced to lower the dose, making treatment less effective,” said senior author Guojun Chen, Assistant Professor in McGill’s Department of Biomedical Engineering and member of the Goodman Cancer Institute. “Our approach could allow for higher, more effective doses while limiting toxicity, which is a major goal in cancer treatment.”

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