Cooling vertical surfaces
Related Articles
Sky cooling for LED streetlights
Thermal management is a critical challenge for semiconductor light-emitting diodes (LEDs), as inadequate heat dissipation reduces luminous efficiency and shortens the devices’ lifespan. Thus, there is an urgent need for more effective cooling strategies to enhance the energy efficiency of LEDs. LED streetlights, which operate primarily at night and experience high chip temperatures, could benefit greatly from improved thermal management. In this study, we introduce a sky-facing radiative cooling strategy for outdoor LED streetlights, an innovative yet less explored approach for thermal management of optoelectronics. Our method employs a nanoporous polyethylene (nanoPE) material that possesses both infrared transparency and visible reflectivity. This approach enables the direct release of heat generated by the LED through a sky-facing radiative cooling channel, while also reflecting a significant portion of the light back for illumination. By incorporating nanoPE as a cover for sky-facing LED lights, we achieved a remarkable temperature reduction of 7.8 °C in controlled laboratory settings and 4.4 °C in outdoor environments. These reductions were accompanied by an efficiency improvement of approximately 5% and 4%, respectively. This enhanced efficiency translates into substantial annual energy savings, estimated at 1.9 terawatt-hours when considering the use of LED streetlights in the United States. Furthermore, this electricity saving corresponds to a reduction of approximately 1.3 million metric tons of CO2 emissions, equivalent to 0.03% of the total annual CO2 emissions by the United States in 2018.
Efficiently preparing chiral states via fermionic cooling on bosonic quantum hardware
Simulating many-body systems is one of the most promising applications of near-term quantum computers. An important open question is how to efficiently prepare the ground states of arbitrary fermionic Hamiltonians, especially those with nontrivial topology. Here, we propose an efficient protocol for preparing low-energy states of fermionic Hamiltonians on a noisy bosonic quantum simulator by adiabatic cooling using a simulated bath. We arrange the couplings such that the simulated system and bath together obtain a local fermionic description in which fermionic excitations can be extracted individually, via coherent hopping to the bath, rather than in pairs as would otherwise be required by fermion parity conservation. This approach thus achieves a linear (rather than quadratic) scaling of the cooling rate vs. excitation density at low densities. We show that certain topological phases such as the chiral (non-Abelian) phase of the Kitaev honeycomb model can be prepared efficiently using our protocol. Our protocol performs favorably in the presence of noise, making it suitable for execution on near-term quantum devices.
Expert consensus on orthodontic treatment of protrusive facial deformities
Protrusive facial deformities, characterized by the forward displacement of the teeth and/or jaws beyond the normal range, affect a considerable portion of the population. The manifestations and morphological mechanisms of protrusive facial deformities are complex and diverse, requiring orthodontists to possess a high level of theoretical knowledge and practical experience in the relevant orthodontic field. To further optimize the correction of protrusive facial deformities, this consensus proposes that the morphological mechanisms and diagnosis of protrusive facial deformities should be analyzed and judged from multiple dimensions and factors to accurately formulate treatment plans. It emphasizes the use of orthodontic strategies, including jaw growth modification, tooth extraction or non-extraction for anterior teeth retraction, and maxillofacial vertical control. These strategies aim to reduce anterior teeth and lip protrusion, increase chin prominence, harmonize nasolabial and chin-lip relationships, and improve the facial profile of patients with protrusive facial deformities. For severe skeletal protrusive facial deformities, orthodontic-orthognathic combined treatment may be suggested. This consensus summarizes the theoretical knowledge and clinical experience of numerous renowned oral experts nationwide, offering reference strategies for the correction of protrusive facial deformities.
Energy efficiency and carbon savings via a body grid
The climate crisis necessitates decarbonization solutions that transform energy systems across all scales. While attention today focuses on utility-scale power systems, mini-or metro-scale grids, and at end-use device efficiency, the individual user scale remains underexplored. Just as with energy efficiency innovations tailored to micro-environments, body-scale energy savings offer new opportunities alongside technological and behavioral challenges. Here we propose a technique and a suite of potential innovations focused on the “body grid” in which devices, circuits, information network, human body and the environment interact within a universal framework to achieve energy savings, new functionality, and improved comfort. We present and test a prototype body grid supporting inter-device synergy and cooperation with external energy systems indoors and outdoors. This system yields substantial energy and economic savings, enhances personal control and comfort, and enables potential energy market participation. Simulation results demonstrate global energy savings of up to 50% for space cooling and heating.
Anti-icing properties of nonionic/hydrophilic concentrated polymer brushes and mechanistic insights via their swollen-state analysis
Anti-icing surfaces are important to prevent snow and ice accumulation, which can pose significant risks. Here, we analyze the anti-icing performance of concentrated polymer brushes (CPBs) consisting of a versatile nonionic/hydrophilic monomer and discuss the low-temperature properties of the CPB-retaining water. The anti-icing functionality is evaluated by measuring the ice adhesion strength as a function of the temperature and the structural parameters (e.g., density and length) of the polymer brushes. We demonstrate that only the CPB region (σ* ≥ 0.15) exhibits both high anti-icing functionality and excellent durability. Furthermore, the thickening of the CPBs is key to achieving a detailed characterization of the water present in the CPBs at low temperatures using in situ microscopic Fourier-transform infrared spectroscopy and differential scanning calorimetry. These results suggest that the water effectively remaining via quasi-equilibrium partial deswelling formed a lubricating layer, contributing to high anti-icing functionality and durability.
Responses