Science Daily February 6, 2020 Current methods for placing nano-sized semiconductors on metallic particles to utilize them in nano-lasing and nano-lithography lack precision or are too costly. Researchers in Japan have developed a method based on a hydrothermal synthesis reaction to locally and selectively synthesize zinc oxide in a plasmonic nanoantenna. They first made evident the role of localized surface plasmon resonances (LSPR) for achieving efficient heating of gold nanostructures. Then, by selectively addressing one of the LSPRs of a gold antenna, they demonstrated that localized zinc oxide formation at the targeted location of the antenna can be achieved due […]
Hackers could shut down satellites–or turn them into weapons
Phys.org February 12, 2020 According to researchers at the University of Denver the lack of cybersecurity standards and regulations for commercial satellites, in the U.S. and internationally, leaves them highly vulnerable to cyberattacks. If hackers took control of the satellites, they could shut them down, deny access to their services, jam or spoof the signals from satellites, creating havoc for critical infrastructure. If hackers took control of steerable satellites, they could alter the satellites’ orbits and crash them into other satellites. Complex supply chains and layers of stakeholders, and multiple parties involved in their management means it is often not […]
Movement of a liquid droplet generates over 5 volts of electricity
EurekAlert February 13, 2020 Researchers in Japan have demonstrated that using molybdenum disulfide instead of graphene as the active material in the generator makes it possible to generate over 5 volts of electricity from a liquid droplet. They made a large area single -layer MoS2 film with polystyrene film as bearing material, by chemical vapor deposition using a sapphire substrate with molybdenum oxide (MoO3) and sulphur powders. The film made it easy to transfer the synthesized MoS2 film to the surface. The generator is flexible enough to be installed on the curved inner surface of plumbing and is thus expected […]
New droplet-based electricity generator: A drop of water generates 140V power, lighting up 100 LED bulbs
Science Daily February 5, 2020 An international team of researchers (USA – University of Nebraska, Hong Kong, China) found that the continuous droplets impinging on Polytetrafluoroethylene (PTFE) provides a new route for the accumulation and storage of high-density surface charges. The device consists of an aluminium electrode, and an indium tin oxide (ITO) electrode with a film of PTFE deposited on it. The PTFE/ITO electrode is responsible for the charge generation, storage, and induction. When a falling water droplet hits and spreads on the PTFE/ITO surface, it naturally “bridges” the aluminium electrode and the PTFE/ITO electrode, translating the original system […]
Predicting Contagion Speed
American Physical Society February 12, 2020 To effectively monitor, design, or intervene in epidemic-like processes, there is a need to predict the speed of a particular contagion in a particular network, and to distinguish between nodes that are more likely to become infected sooner or later during an outbreak. Researchers in the UK studied global transport and communication networks using a message-passing approach to derive simple and effective predictions that are validated against epidemic simulations on a variety of real-world networks with good agreement. In addition to individualized predictions for different nodes, they found an overall sudden transition from low […]
Quantum memories entangled over 50-kilometer cable
Phys.org February 13, 2020 Researchers in China have demonstrated entanglement of two atomic ensembles in one laboratory via photon transmission through city-scale optical fibres. The atomic ensembles function as quantum memories that store quantum states. They used cavity enhancement to efficiently create atom–photon entanglement and quantum frequency conversion to shift the atomic wavelength to telecommunications wavelengths. They realized entanglement over 22 kilometres of field-deployed fibres via two-photon interference and entanglement over 50 kilometres of coiled fibres via single-photon interference. The experiment could be extended to nodes physically separated by similar distances, which would thus form a functional segment of the […]
Researchers develop smaller, lighter radiation shielding
Science Daily February 12, 2020 Commonly used shielding in aerospace devices consists of putting an aluminum box around any sensitive technologies has been viewed as providing the best tradeoff between a shield’s weight and the protection it provides. A team of researchers in the US (industry, North Carolina State University) has developed a technique that relies on mixing oxidized metal powder — rust — in a polymer, and then incorporating it into a common conformal coating on the relevant electronics. Radiation transport calculations show that inclusion of the metal oxide powder provides shielding comparable to a conventional shield, at low […]
Scientists develop first electrically-driven ‘topological’ laser
Phys.org February 13, 2020 Previous demonstrations of topological lasers have required an external laser source for optical pumping and have operated in the conventional optical frequency regime. An international team of researchers (Singapore, UK) demonstrated an electrically pumped terahertz quantum cascade laser based on topologically protected valley edge states. Unlike topological lasers that rely on large-scale features to impart topological protection, the compact design makes use of the valley degree of freedom in photonic crystals, analogous to two-dimensional gapped valleytronic materials. With regularly spaced emission peaks lasing occurs in a sharp-cornered triangular cavity, even if perturbations are introduced into the […]
Something from nothing: Using waste heat to power electronics
EurekAlert February 12, 2020 A thermocell can convert environmental thermal energy to electric energy via thermal charging effect. However, the output voltage is low and depends on temperature. Researchers in Japan developed a thermocell containing a material that exhibited a temperature-induced phase transition of its crystal structure. Just above room temperature, the atoms in this solid material rearranged to form a different crystal structure. This phase transition resulted in an increase in output voltage from zero to around 120 mV, representing a considerable performance improvement over that of existing thermocells. They were able to finely tune the phase transition temperature […]
Using long-wavelength terahertz radiation to produce video with a high frame rate
Phys.org February 10, 2020 Long-wavelength terahertz radiation which is considered to be much safer than X-ray radiation has not been used in security and medical devices because its energy is so low and it has been difficult to create high-resolution images using them. Instead of building a more sensitive sensor researchers in the UK made the waves more readable to conventional technology. They converted the terahertz radiation into green light by directing it into a cloud of excited cesium atoms. Once the cloud was formed, the researchers fired a secondary terahertz laser through a moving object, which allowed a “shadow […]