news, journals and articles from all over the world.
In Applied Physics Letters, researchers report achieving self-sustaining and long-term levitation of millimeter-sized droplets of several different liquids without any external forces. To get the droplets to levitate, they use solutocapillary convection, which occurs when a surface tension gradient is formed by nonuniform distribution of vapor molecules from the droplet at the pool surface.
In Applied Physics Letters, researchers in the U.K. introduce a novel imaging method to detect gold nanoparticles in woodlice. Their method, known as four-wave mixing microscopy, flashes light that the gold nanoparticles absorb. The light flashes again and the subsequent scattering reveals the nanoparticles’ locations. With information about the quantity, location, and impact of gold nanoparticles within the organism, scientists can better understand the potential harm other metals may have on nature.
In Applied Physics Letters, researchers highlight the latest nanostructured components integrated on image sensor chips that are most likely to make the biggest impact in multimodal imaging and detailed a promising approach to detect multiple-band spectra by fabricating an on-chip spectrometer. The developments could enable autonomous vehicles to see around corners instead of just a straight line, biomedical imaging to detect abnormalities at different tissue depths, and telescopes to see through interstellar dust.
In Applied Physics Letters, researchers outline how a robot could be taught to navigate through a maze by electrically stimulating a culture of brain nerve cells connected to the machine. These nerve cells were grown from living cells and acted as the physical reservoir for the computer to construct coherent signals. These findings suggest goal-directed behavior can be generated without any additional learning by sending disturbance signals to an embodied system.
Researchers from China present the fastest real-time quantum random number generators to date to make the devices quicker and more portable. The device combines a state-of-the-art photonic integrated chip with optimized real-time postprocessing for extracting randomness from quantum entropy source of vacuum states.
Cryocoolers are ultracold refrigeration units used in surgery and drug development, semiconductor fabrication, and spacecraft. The regenerative heat exchanger, or regenerator, is a core component of cryocoolers. At temperatures below 10 kelvins, performance drops precipitously, with maximum regenerator loss of more than 50%. In Applied Physics Letters, researchers used superactivated carbon particles as an alternative regenerator material to increase cooling capability at temperatures as low as 4 kelvins.
As environmental and energy crises become more common, a thermal energy harvester capable of converting abundant thermal energy into mechanical energy appears to be a promising mitigation strategy. The majority of thermal power generation technologies involve solid moving parts, which can reduce reliability and lead to frequent maintenance. This inspired researchers in China to develop a thermal power nanogenerator without solid moving parts. In Applied Physics Letters, they propose a thermal power nanogenerator that converts thermal energy into electrical energy.
Michael Hill, technical director of Skyworks Solutions, and his colleagues provide an overview in Applied Physics Letters on nascent 5G technologies and show how enhancing ceramic materials could play a pivotal role in development. They have developed a ceramic called a circulator, a three-port device that serves as a traffic circle to keep the signal flowing in one direction and enable a receiver and a transmitter to share the same antenna.
Singing may be the next-generation, noninvasive approach to determining the health of a patient’s thyroid. When a person sings, the vibrations create waves in the tissue near the vocal tract called shear waves. If a tumor is present in the thyroid, the elasticity of its surrounding tissue increases, stiffening, and causing the shear waves to accelerate. Using ultrasound imaging to measure these waves, researchers can determine the elasticity of the thyroid tissue. They demonstrate the technique in Applied Physics Letters.
A small and inexpensive sensor, announced in Applied Physics Letters and based on an electrochemical system, could potentially be worn continuously by cardiac patients or others who require constant monitoring. A solution containing electrolyte substances is placed into a small circular cavity that is capped with a thin flexible diaphragm, allowing detection of subtle movements when placed on a patient’s chest. The authors suggest their sensor could be used for diagnosis of respiratory diseases.
Glass windows typically offer some amount of sound proofing, sometimes unintentionally. In general, ventilation is required to achieve large sound transmission. But some applications — like gas explosion studies — require a transparent partition that allows for acoustic propagation without the presence of airflow. In those cases, ventilation is not allowed. In Applied Physics Letters, researchers discuss a layered glass material they developed that allows for efficient sound transmission with no air ventilation.
Thermoelectric devices, which use the temperature difference between the top and bottom of the device to generate power, offer some promise for harnessing naturally occurring energy. In Applied Physics Letters, authors tested a device made up of a wavelength-selective emitter that constantly cools the device during the day using radiative cooling. As a result, the top of the device is cooler than the bottom, causing a temperature difference that creates constant voltage through day and night and various weather conditions.
Using the same technology that allows high-frequency signals to travel on regular phone lines, researchers tested sending extremely high-frequency, 200 GHz signals through a pair of copper wires. The result is a link that can move data at rates of terabits per second, significantly faster than currently available channels. In Applied Physics Letters, the scientists discuss their work using experimental measurements and mathematical modeling to characterize the input and output signals in a waveguide.
Mapping the electrical conductivity of the heart would be a valuable tool in diagnosis and disease management, but doing so would require invasive procedures, which aren’t capable of directly mapping dielectric properties. Significant advances have recently been made that leverage atomic magnetometers to provide a direct picture of electric conductivity of biological tissues, and in Applied Physics Letters, new work in quantum sensors points to ways such technology could be used to examine the heart.
The field of “brain-mimicking” neuromorphic electronics shows great potential for basic research and commercial applications, and researchers in Germany and Switzerland recently explored the possibility of reproducing the physics of real neural circuits by using the physics of silicon. In Applied Physics Letters, they present their work to understand neural processing systems, as well as a recipe to reproduce these computing principles in mixed signal analog/digital electronics and novel materials.
Researchers in China demonstrated a robotic gripping mechanism that mimics how a sea anemone catches its prey. The bionic torus captures and releases objects by crimping its skin. The grasper not only is relatively cheap and easy to produce but also can grab a variety of objects of different sizes, shapes, weights and materials. They discuss their work in this week’s Applied Physics Letters.
Doctors have used focused ultrasound to destroy tumors without invasive surgery for some time. However, the therapeutic ultrasound used in clinics today indiscriminately damages cancer and healthy cells alike. Researchers have now developed a low-intensity ultrasound approach that exploits the properties of tumor cells to target them and provide a safer option. Their findings, reported in Applied Physics Letters, are a new step in oncotripsy, the singling out and killing of cancer cells based on their physical properties.
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