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Category: materials

Physicists watch light drift in quantized steps for the first time

In physics, the classical “Hall effect,” discovered in the late 19th century, describes how a transverse voltage is generated when an electric current is exposed to a perpendicular magnetic field. Simply put, the magnetic field causes the electrons, which are negatively charged, to drift sideways, creating a negative charge on one edge of the conducting strip and a positive charge on the opposite side.

For decades, this voltage difference has been used as a diagnostic tool to measure magnetic fields with precision and characterize material doping levels, that is, the addition of a tiny, controlled amount of impurity to a pure material to change how it conducts electricity.

In the 1980s, experiments at ultra-low temperatures with ultra-thin conductors—imagine a sheet of paper—revealed that under intense magnetic fields, this voltage difference increases not in a straight line but in perfectly defined steps.

The Future Of Band-AIDS: Current And Future Examples

Unless you’ve been extremely lucky, you’ve likely been wounded, be it a knife cut while cooking or a sports injury. To remedy this unpleasant experience, you’ve taken some version of the following steps: clean the wound, disinfect the area, and apply a plaster or bandage. While a common and simple first-aid skill, this wound healing process has existed since ancient times.

Furthermore, there are wound cases, especially chronic wounds that arise from conditions such as diabetes, that can be more severe than one might expect. The 5-year survival rate of patients with chronic wounds is about 70%, which is worse than that of breast cancer, prostate cancer and other diseases. In addition, treating wounds adds to the cost of care, leading to about $28 billion per year in the U.S. alone.

Following the traditional use case, the main function of bandages for acute or chronic wound care has been to protect the injured area from external factors that could worsen the injury, such as dirt, bacterial infection and friction. Over the centuries since the inception of wound dressing, some changes have taken place. These have mostly related to the material of bandages, such as stronger-adhering waterproof ones; but the role of the bandage has retained its passive role.

MIT’s 3D Printer Can Produce Complete and Functional Electric Motors

3D printers are not Star Trek-style replicators. Most 3D printers can only fabricate parts in a single material and that material is usually some form of plastic. But multi-material 3D printers do exist and by taking that idea to its limits, a team of researchers at MIT was able to build this 3D printer that can produce complete and functional electric motors.

The team didn’t have to start from scratch, because they were able to use an E3D ToolChanger 3D printer as the foundation for this project. That printer model came out several years ago and is now discontinued, but it was and still is pretty unique. It can swap between toolheads on-the-fly to print with different materials, which is a capability most users take advantage of to print with multiple colors or multiple kinds of thermoplastic filament material, such as PLA and PETG.

Metamaterial image sensor keeps colors clear even under oblique light

Smartphone cameras are becoming smaller, yet photos are becoming sharper. Korean researchers have elevated the limits of next-generation smartphone cameras by developing a new image sensor technology that can accurately represent colors regardless of the angle at which light enters. The team achieved this by utilizing a “metamaterial” that designs the movement of light through structures too small to be seen with the naked eye.

A research team led by Professor Min Seok Jang of the School of Electrical Engineering, in collaboration with Professor Haejun Chung’s team at Hanyang, has developed a metamaterial-based technology for image sensors that can stably separate colors even when the angle of light incidence varies.

The findings were published in Advanced Optical Materials.

Phonon lasers unlock ultrabroadband acoustic frequency combs

Acoustic frequency combs organize sound or mechanical vibrations into a series of evenly spaced frequencies, much like the teeth on a comb. They are the acoustic counterparts of optical frequency combs, which consist of equally spaced spectral lines and act as extraordinarily precise rulers for measuring light.

While optical frequency combs have revolutionized fields such as precision metrology, spectroscopy, and astronomy, acoustic frequency combs utilize sound waves, which interact with materials in fundamentally different ways and are well-suited for various sensing and imaging applications.

However, existing acoustic frequency combs operate only at very high, inaudible frequencies above 100 kHz and typically produce no more than a few hundred comb teeth, limiting their applicability.

Chemists synthesize first stable copper metallocene complex, closing a 70-year gap

Almost half a century ago, a remarkable molecule called metallocene took center stage in chemistry, earning Geoffrey Wilkinson and Ernst Otto Fischer the Nobel Prize. These organic compounds, made of a transition metal “sandwiched” between two flat, ring-shaped organic layers, have since become an integral part of new-age polymers, materials, and pharmaceuticals.

In their recent work published in the Journal of the American Chemical Society, a team from University of California brought metallocene back into the limelight with the synthesis of cuprocenes—the first stable version of neutral copper metallocene with the chemical formula Cpttt 2 Cu where Cpttt stands for C5H2tBu3 or bis(tri-tert-butylcyclopentadienyl) ligand. This new complex of copper has blue-green crystals and is stable at room temperature, away from light.

They also produced two new forms of cuprocene: a colorless, negatively charged version via reduction, and a purple, positively charged version via oxidation.

Obstacle or accelerator? How imperfections affect material strength

Imagine a material cracking—now imagine what happens if there are small inclusions in the material. Do they create an obstacle course for the crack to navigate, slowing it down? Or do they act as weak points, helping the crack spread faster?

Historically, most engineers believed the former, using heterogeneities, or differences, in materials to make materials stronger and more resilient. However, research from Georgia Tech is showing that, in some cases, heterogeneities make materials weaker and can even accelerate cracks.

Led by School of Physics Assistant Professor Itamar Kolvin, the study, “Dual Role for Heterogeneity in Dynamic Fracture,” was published in Physical Review Letters this fall.

What ‘housane’ rings are and why a light-powered route may matter for drugs

When developing new drugs, one thing is particularly important: finding and producing the right molecules that can be used as active ingredients. The key elements of some drugs, such as penicillin, are small, tri- or quadripartite ring molecules. A team led by Prof Frank Glorius from the Institute of Organic Chemistry of the University of Münster (Germany) has now developed a method for efficiently converting readily available basic materials into such small, high-grade ring molecules. The product has a structure reminiscent of a line drawing of a house, hence its name “housane.” The reaction is triggered by a photocatalyst that transfers light energy to the molecules to enable the conversion.

Silicon nanowire based angle robust ultrasensitive hyperbolic metamaterial biosensor

We design an angle-robust hyperbolic metamaterial-based biosensor structure using n-doped silicon nanowires. We examine the hyperbolic properties of the structure using effective medium theory (EMT) and analyze the resonance shift of our proposed biosensor structure, by employing the finite-difference time d.

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