A new metamaterial design eliminates internal distortions that can adversely affect applications in cloaking and sensing.
Category: materials – Page 4
Tiny forces, big effects: How particle interactions control the flow of soft materials
Sitting in a restaurant, you reach for the ketchup bottle, eyeing the basket of fries in front of you. You give the bottle a shake, then a tap. For a moment, nothing happens—the ketchup clings stubbornly to the glass. Then, all at once, it lets go and rushes out, sometimes in a steady stream, sometimes in a messy surge that threatens to flood the basket.
That awkward moment when ketchup stops behaving like a solid and suddenly starts flowing like a liquid is called “yielding.” Scientists see the same kind of behavior in many everyday and advanced materials, from toothpaste, paints and concrete to 3D-printing inks and electrodes used in next-generation batteries. Yet, what actually causes a material to hold its shape one moment and suddenly let go the next has been surprisingly hard to pin down, especially deep inside dense, opaque fluids where particle motion is difficult to see.
A new approach to cancer vaccination yields more powerful T cells
MIT engineers have developed a new way to amplify the T-cell response to mRNA vaccines—an advance that could lead to much more powerful cancer vaccines and stronger protection against infectious diseases.
Most vaccines generate both antibodies and T cells that can target the vaccine antigen by activating antigen-presenting cells, such as dendritic cells. In this study, the researchers boosted the T-cell response with a new type of vaccine adjuvant (a material that can help stimulate the immune system). The new adjuvant consists of mRNA molecules encoding genes that turn on immune signaling pathways and promote a supercharged T-cell response.
In studies in mice, this mRNA-encoded adjuvant enabled the immune system to completely eradicate most tumors, either on its own or delivered along with a tumor antigen. The adjuvant also boosted the T-cell response to vaccines against influenza and COVID-19.
80 years after the Trinity nuclear test, scientists identify new molecule-trapping crystal formed in the blast
Matter behaves strangely under extreme conditions, and often, remnants of these behaviors are left behind even when conditions return to normal. The Trinity nuclear test in 1945 left behind such remnants, and now, 80 years after the explosion, researchers have identified another unique example of what happens when various materials are heated to temperatures exceeding 1,500 °C (2,730 °F) and put under pressures tens of thousands of times atmospheric pressure.
The team describes a clathrate compound never before found among nuclear-explosion products in their new study, published in the Proceedings of the National Academy of Sciences.
Lab-grown diamond device could change how radiation doses are measured
A team led by researchers from Tokyo Metropolitan University, in collaboration with Tohoku University and Orbray Co., Ltd., using heteroepitaxial diamond materials developed by Orbray, have shown that lab-grown diamonds might realize a radiation dosimeter compatible with both medical diagnosis and radiation therapy.
The work is published in the journal Medical Physics.
They demonstrated that a diamond-based dosimeter could accurately measure doses in the same energy range as diagnostic X-rays, with far better sensitivity per volume than conventional detectors. Using the same device for dosimetry during both diagnosis and therapies could enable improved consistency.
Dynamically Tunable Singular States Through Air-Slit Control in Asymmetric Resonant Metamaterials
This study presents a novel method for dynamically tuning singular states in one-dimensional (1D) photonic lattices (PLs) using air-slit-based structural modifications. Singular states, arising from symmetry-breaking-induced resonance radiation, generate diverse spectral features through interactions between resonance modes and background radiation. By strategically incorporating air slits to break symmetry in 1D PLs, we demonstrated effective control of resonance positions, enabling dual functionalities including narrowband band pass and notch filtering. These singular states originate from asymmetric guided-mode resonances (aGMRs), which can be interpreted by analytical modeling of the equivalent slab waveguide. Moreover, the introduction of multiple air slits significantly enhances spectral tunability by inducing multiple folding behaviors in the resonance bands.
Void-Filled Material Stops Intense Electron Beam
An intense electron beam is stopped more efficiently by a highly porous material than by a less porous material, suggesting new strategies for controlling beams.
New experiments show that porous materials consisting mostly of empty space can absorb the energy carried by an ultraintense electron beam more effectively than porous media with higher mass densities. The finding contradicts the prevailing notion that denser and thicker obstacles always provide more stopping power and suggests that the microstructure of a material fundamentally changes its electron-stopping ability. Simulations by the experimental team revealed the physical mechanisms behind this “anomalous-stopping” effect, which the researchers believe provides a new way to control the propagation of electron beams in extreme environments [1].
The study focuses on relativistic electron beams (REBs), which travel at close to the speed of light. REBs that carry currents in the mega-ampere regime can deliver petawatts (1015 watts) of power to a small target in a pulse lasting for a few picoseconds. This high intensity makes them ideal for creating and probing extreme states of matter that exist in stars, planetary cores, or nuclear events. The short bursts of intense energy provided by REBs are also used in inertial-confinement fusion—a scheme in which high-power lasers heat a fuel pellet and trigger nuclear fusion.