Search

Spinning thermal radiation is a unique phenomenon in the symmetry-broken system, which is of both fundamental and applied interest. Its potential applications include chiral nanoparticle probing and radiation detection. However, these applications are often restricted by limited circular dichroism and quality factor. In this paper, the spinning thermal radiation of twisted hyperbolic heterostructures is investigated. By adjusting the twist angle, we demonstrate the near-perfect circular dichroism (CD = 0.99) and the high quality factor at a wavelength of 20 μm. The epsilon-near-zero mode of α-phase molybdenum trioxide allows for excellent spin-selective thermal radiation. The co-polarization and cross-polarization have proven it in the reflected wave and the distribution of the electric field components. The strong spinning thermal radiation originates from the cross-polarization conversion between the left-handed circularly polarized and right-handed circularly polarized waves. This work provides a general approach to spinning thermal radiation for future energy applications. [ABSTRACT FROM AUTHOR]

Smart radiation devices (SRDs) for spacecraft, which utilize thermochromic films with adaptive emissivity switching capability and minimal resource consumption, have garnered attention. However, there remains a lack of systematic strategies for more efficient SRDs design. In this study, we focus on a typical SRD, namely VO 2 /BaF 2 /Ag, to exemplify and investigate two optimization methods: the quarter-wave condition and the traversal method. By employing the quarter-wave condition, the intermediate dielectric layer thickness required to induce Fabry-Perot resonance is determined as 1.81 μm. In this case, the emission modulation is 0.62, and the solar absorption is 0.29. However, utilizing the traversal method, optimized thicknesses for VO 2 and BaF 2 are found to be 0.02 μm and 1.60 μm, respectively. It is found that the emission modulation can reach 0.64, while the solar absorption remains unchanged at 0.29. Notably, the traversal method yields superior emission modulation of SRD compared to the quarter-wave condition, while there is no difference in solar absorption of SRD obtained by the two optimization methods. Consequently, the quarter-wave condition can provide an approximate range for the thickness of the dielectric layer in SRD designs, with further optimization achieved through the traversal method to enhance SRD performance. Overall, our research supplies valuable theoretical guidance for SRD design and aims to propel advancements in spacecraft thermal control. [ABSTRACT FROM AUTHOR]

• We have demonstrated a THz device with strong chirality and asymmetric transmission effect based on a twisted bilayer α-MoO 3. • It is found that the proposed structure achieves a giant circular dichroism value of 0.81 at 9.8 THz. • The strong chirality originates from the symmetry breaking of the structure. • The asymmetric transmission for circularly polarized wave can reach 0.55 at 9.2 THz. Chirality and asymmetric transmission have wide-ranging applications in fields such as optics, chemical synthesis, pharmaceutical research, biological analysis, materials science and communication technology. In this work, we have demonstrated a terahertz (THz) device with strong chirality and asymmetric transmission effect based on a twisted bilayer α-MoO 3. The unique optical response can be realized by adjusting structural parameters such as the thicknesses of the layers as well as the angle of relative rotation. It is found that the proposed structure achieves a giant circular dichroism (CD) value of 0.81 at 9.8 THz, which originates from the symmetry breaking of the structure. The phenomenon has been approved by the polarization conversion and the distributions of the electric field. In addition, the device exhibits the asymmetric transmission effect for circularly polarized wave incidence. The results show that the forward and backward transmissivity of circularly polarized waves with different handedness exhibit a significant difference of up to 0.55 at 9.2 THz. This work simultaneously achieves chirality and asymmetric transmission effect in the terahertz band, which paves the way for developing terahertz devices capable of chirality manipulation and optical isolation. [ABSTRACT FROM AUTHOR]

Titanium nitride (TiN) serves as an ideal reagent for photothermal therapy due to its cost-effectiveness, stability, and biocompatibility. This study investigates the optical and thermal properties of TiN nanoparticles in the near-infrared (NIR) region. Specifically, we employ the COMSOL Multiphysics software to solve Maxwell's equations using a finite element method, enabling us to investigate the photothermal characteristics of individual TiN nanorods. To ensure accurate photothermal coupling calculations, we utilize the Fourier steady-state heat conduction equation. The results demonstrate that the nanorod photothermal properties exhibit significantly enhanced effects when the incident light is polarized along the long axis of the rod, while the thermal properties of the nanorods are primarily influenced by their optical absorption efficiency. The tunability investigation of the nanorods demonstrates that an increase in aspect ratio (AR) results in a red-shift of the absorption peaks. Concurrently, there is an expansion in the bandwidth corresponding to the absorption peak, accompanied by an augmentation in its peak value. It is evident that at AR = 5, the TiN nanorods exhibit enhanced photothermal properties in the NIR region, resulting in a temperature increase of 43 K in the surrounding medium through efficient heat transfer. Consequently, this accomplishment enables achieving the desired temperature range for effective photothermal therapy. The significance of this study lies in providing a valuable reference and theoretical guidance for exploring the utilization of TiN nanorods in photothermal therapy, with a specific focus on attaining a more precise understanding of temperature elevation and distribution during the treatment process. [ABSTRACT FROM AUTHOR]

[Display omitted] • We study the ITRs of AlN/graphene/SiC heterostructures by molecular dynamics simulation. • The ITRs decrease with the increase of the numbers when the height of the NNFSs is lower than the cutoff distance. • The ITRs increase significantly when the height of the NNFSs is higher than the cutoff distance of the interaction. • The change of the ITRs arises from the combined effect of sub-interfacial interactions and the overlaps of PDOS. Revealing the heat transport mechanism in typical heterostructures is crucial for designing GaN power chips with better engineering heat transfer performance. Herein, the effect of nanoscale nonplanar feature structures (NNFSs) on the interfacial thermal resistances (ITRs) of w-AlN/bilayer graphene/3C-SiC heterostructures is investigated systematically by molecular dynamics. The results indicate that the increase of the NNFSs numbers contributes to the decrease of the ITRs when the height is lower than the cutoff distance of the interaction. Multiple analyses indicate that, although the interactions at two van der Waals sub-interfaces (w-AlN/graphene and graphene/graphene) slightly weaken the phonon transfer, the increase of the NNFSs numbers enlarge the overlaps of phonon density of state (PDOS), which provides more phonon transfer channels. However, when the height is higher than the cutoff distance, the ITRs increase significantly due to the double decrease of the interactions and the overlaps of PDOS for the w-AlN/graphene sub-interface. These phenomena are further verified by the transient transport of energy. Besides, the NNFSs with random distribution also contribute to the reduction of the ITRs. We believe that the results of this work will provide significant guidance for improving the thermal transport performance of GaN power chips. [ABSTRACT FROM AUTHOR]

In this paper, we present Polarized message-passing (PMP), a novel paradigm to revolutionize the design of message-passing graph neural networks (GNNs). In contrast to existing methods, PMP captures the power of node-node similarity and dissimilarity to acquire dual sources of messages from neighbors. The messages are then coalesced to enable GNNs to learn expressive representations from sparse but strongly correlated neighbors. Three novel GNNs based on the PMP paradigm, namely PMP graph convolutional network (PMP-GCN), PMP graph attention network (PMP-GAT), and PMP graph PageRank network (PMP-GPN) are proposed to perform various downstream tasks. Theoretical analysis is also conducted to verify the high expressiveness of the proposed PMP-based GNNs. In addition, an empirical study of five learning tasks based on 12 real-world datasets is conducted to validate the performances of PMP-GCN, PMP-GAT, and PMP-GPN. The proposed PMP-GCN, PMP-GAT, and PMP-GPN outperform numerous strong message-passing GNNs across all five learning tasks, demonstrating the effectiveness of the proposed PMP paradigm. • A novel paradigm PMP is proposed to enable GNNs to learn more expressive representations. • Novel GNN architectures, namely PMP-GCN, PMP-GAT, and PMP-GPN are constructed for various downstream tasks. • The expressiveness of the PMP-based GNNs is theoretically guaranteed. [ABSTRACT FROM AUTHOR]

The triangular pyramid nanostructure (TPN) raises a perfect prerequisite for the aggregation of surface plasmon resonances (SPRs). However, the application of TPN in thermoplasmonics has not yet been developed. The aim of this study is to explore the development potential of TPNs for enhanced noble metal photothermal applications. We investigated the optical absorption properties, photothermal conversion efficiency, and photothermal response under continuous wave irradiation of TPNs based on Ag and Au nanomaterials. The results show that TPN helps to enhance the SPR excitation of Ag and Au in the near-infrared. TPN based on noble metal nanomaterials shows good light absorption capacity and photothermal response. The photothermal conversion efficiencies of the TPN nanoparticle suspensions increased by 56.95% (Ag) and 49.57% (Au), respectively, compared to the same volume of noble metal nanospheres. This work is intended to researchers better understand the development potential of TPN in thermoplasmonics applications. [ABSTRACT FROM AUTHOR]

• TE and TM polarization both have nonreciprocal thermal radiation. • Nonreciprocity is greater than 85 % with ultra-high Q factor at angle of 0.8°. • The accuracy of calculation results can be well proved by coupled-mode theory. • The impedance matching theory is used to explain the physical mechanism well. Nonreciprocal thermal radiation is valuable to the energy transmission and collection. Issues of single polarization in near-infrared band with large incident angle cast limitations on the development of nonreciprocal thermal radiation. A dual-polarization narrow-band nonreciprocal thermal radiator in near-infrared band with extremely small incident angle is proposed to address these issues. The radiator consists of periodic annular arrays, magneto-optical medium and metal reflective layer. The simulation results show that the nonreciprocity of two polarizations is greater than 85 % with ultra-high Q factor at the angle of 0.8°. The finite element method and coupled mode theory that are adopted in the study offer high consistent results, which prove the accuracy of calculation results. The physical mechanism of near-infrared narrow-band nonreciprocal radiation is attributed to the excitation of cavity resonance and guided mode resonance. The proposed two-dimensional near-infrared nonreciprocal radiator that allows the dual-polarization operation at small incident angle offers it good potentials in thermal photovoltaic system and energy conversion. [ABSTRACT FROM AUTHOR]

Ginger is consumed as a spice and medicine globally. However, pesticide residues in ginger and their residue changes during processing remain poorly understood. Our results demonstrate that clothianidin, carbendazim and imidacloprid were the top detected pesticides in 152 ginger samples with detection rates of 17.11–27.63%, and these pesticides had higher average residues of 44.07–97.63 μg/kg. Although most samples contained low levels of pesticides, 66.45% of the samples were detected with pesticides, and 38.82% were contaminated with 2–5 pesticides. Peeling, washing, boiling and pickling removed different amounts of pesticides from ginger (processing factor range: 0.06–1.56, most <1). By contrast, pesticide residues were concentrated by stir-frying and drying (0.50–6.45, most >1). Pesticide residues were influenced by pesticide physico-chemical parameters involving molecular weight, melting point, degradation point and octanol–water partition coefficient by different ginger processing methods. Chronic and acute dietary risk assessments suggest that dietary exposure to pesticides from ginger consumption was within acceptable levels for the general population. This study sheds light on pesticide residues in ginger from market to processing and is of theoretical and practical value for ensuring ginger quality and safety. [Display omitted] • Clothianidin, carbendazim and imidacloprid were the top detected pesticides. • Of the samples, 66.45% were detected with pesticides, and 38.82% were contaminated with 2–5 pesticides. • Pesticide residues were concentrated by stir-frying and drying. • Pesticide residues were influenced by pesticide physico-chemical parameters. • Chronic and acute dietary risks were considered to be acceptable. [ABSTRACT FROM AUTHOR]

• The effect of slotting on the optical properties of silver nanopillars is studied. • Slotting can enhance the resonance absorption peaks of silver nanopillars. • The best slotting method offers a 13 % improvement compared to nanopillars. • This work shows slotting has a promising prospect in solar thermal utilization. Metal nanoparticles (MNPs) have attracted enormous research interest due to their excellent plasma properties. However, in the thermal utilization of solar energy, the narrowband absorption of MNPs limits their application. The investigation of MNP absorption through adjustment in the broadband spectrum holds significant scientific and practical implications. In this work, we study the effect of slotting on the light absorption and photothermal properties of silver nanopillars. The results show that the increase in the number of slots is beneficial to reduce scattering and improving the resonance absorption of silver nanopillar. Through the calculation of photothermal conversion efficiency, it is found that different slotting methods have different levels of improvement compared with silver nanopillars. The utilization of a combination of transverse and longitudinal slotting techniques leads to a 13 % enhancement in the photothermal conversion efficiency of silver nanopillars. The electric field distribution and temperature distribution at resonant wavelengths shows that the excellent light absorption ability of the slot nanopillars is caused by the "lightning rod" effect at the tip of the slit and the excitation of multiple plasmon resonances. The existence of slots is beneficial to compensate for the photothermal response of silver nanopillars in the near-infrared region. Our study proves that slotting helps enhance the application of silver nanopillars in solar thermal utilization. [ABSTRACT FROM AUTHOR]

MXene has received a lot of attention from researchers in the fields of photothermal and photovoltaic due to its excellent optical properties. However, research on MXene-based solar absorbers has rarely been carried out. In this work, we proposed a MXene-based solar absorber with absorption broadband, wide-angle, and polarization insensitive. The absorber has excellent light capture capability, with its average absorption in the solar band as high as 97.8 % and an energy absorption ratio of 98.9 % in the AM1.5 solar radiation spectrum. The electric and magnetic field distributions indicate that the unique hierarchical nanohole design can effectively excite multiple resonance couplings of surface plasmon resonance, cavity resonance, and guided mode resonance. The proposed absorber can still maintain the broadband absorption characteristics within a certain manufacturing tolerances. Moreover, the absorber is insensitive to polarization and has a high light absorption under a large incident angle. We believe that this work holds great promise for solar thermal conversion and heat utilization. [ABSTRACT FROM AUTHOR]

• The effect of protective layer on the performance of smart radiation devices is comprehensively evaluated. • The emission regulation can be enhanced to 0.65, while the solar absorption can be decreased to 0.18. • The performance of the proposed SRD meets the requirement of the spacecraft thermal control devices. • This work provides a theoretical basis for the design of more reasonable spacecraft thermal control devices. With the arrival of the space economy, the miniaturization of spacecraft and their multi-functional trends have put a greater demand on space thermal control systems. Smart radiation devices (SRDs) are gaining attention as a low-cost, light-weight material for the thermal control of spacecraft. Previous works have focused on how to enhance IR emittance tunability of SRDs. In fact, the SRDs performance and lifetime may be affected by the external space environment. Thus, researchers proposed to cover the SRDs with a protective layer to resist oxidation and other problems. However, the influence of protective layer on the performance of SRDs, including IR emittance tunability Δ ε and solar absorption α s , has not been studied systematically yet. In this paper, the impact of protective layer on the performance of SRDs is comprehensively evaluated in theory. Firstly, a three-layer SRD is composed of a vanadium dioxide (VO 2) film, BaF 2 , and a silver (Ag) substrate, which is optimized using the transfer matrix method. The IR emittance tunability and solar absorption can reach 0.64 and 0.29, respectively. Secondly, the smart thermal control device with three protection materials (BaF 2 , Al 2 O 3 and Si) is investigated. The results show that the performance of SRD can be enhanced or deteriorated, depending on the types of protection materials and the thickness. When the protection material is Si, the IR emittance tunability can be enhanced to 0.65, while the solar absorption can be decreased to 0.18. The performance of the proposed SRD meets the requirement of the spacecraft thermal control devices. We believe that this work provides a theoretical basis for the design of more reasonable spacecraft thermal control devices. [ABSTRACT FROM AUTHOR]

To improve the performance of the power cycle and accelerate the realization of the carbon neutrality goal, the development and application of nanofluids are imminent. In this research, we established a supercritical nanofluid spectral absorbance prototype and prepared seven supercritical carbon dioxide nanofluids for various valuable works. The experiments indicated that titanium carbide/supercritical carbon dioxide had the most outstanding stability with the shortest stabilization time (3.2 min) and the smallest fluctuation amplitude in spectral irradiance (±6.33%). Graphene/supercritical carbon dioxide emerged as the most competitive choice in terms of deposition characteristics and spectral absorption capacity, boasting a deposition density and spectral absorbance of 8.146% and 86.39%. Titanium was the most suitable raw material for constructing the prototype. Then, a performance factor was introduced to quantify the contribution of stability and deposition characteristics, and hydroxylated multi-walled carbon nanotube/supercritical carbon dioxide was found to have the most outstanding comprehensive performance with promising applications. Finally, we combined particle swarm optimization and artificial neural networks to develop an improved machine learning optimization model. Compared to the original prediction model, the root mean square error and mean absolute error of this model were reduced by 64.02% and 66.8%. Significantly, the spectral irradiance through the supercritical carbon dioxide nanofluid was reduced by 68.21% compared to the base working fluid, providing guidelines for improving the performance of the power cycle. [Display omitted] • Seven supercritical carbon dioxide nanofluids are prepared and analyzed for their performance. • Introducing a performance factor to comprehensively assess the performance contribution. • Machine learning optimization model is improved to forecast spectral absorbance of nanofluids. [ABSTRACT FROM AUTHOR]

Solar-powered water treatment technology is gaining increasing importance as one solution to ameliorate water resource deficits. This study presents a novel approach of synergistically combining interface solar vaporization technology with low-cost sorption techniques to better enable resource recovery in the water treatment process. After preparation of a halloysite nanotube-based hydrogel, it was subjected to 1 sun illumination. The prepared hydrogel demonstrated an evaporation rate and evaporation efficiency of 2.97 kg/m2·h and 93.2%, respectively, with ideal salt and stain resistance. Under the synergistic effect of halloysite nanotubes (HNTs), the hydrogel efficiently sorbed Li+ at a rate and maximum capacity of 84.15% and 168.3 mg/g, respectively during the solar vaporization process. This study also discussed the main interactions between Li+ and hydrogel sorbents. The results of this study providing a novel and promising approach for concurrent water treatment and Li+ extraction. Schematic diagram of the NPH evaporative and sorption mechanism [Display omitted] • The synthesized hydrogel (PPy@HNTs/PVA) has full spectrum light absorption, low enthalpy of evaporation and excellent sorption property. • The hydrogel exhibits an evaporation rate of 2.97 kg/m2·h under one sun, with an impressive evaporation efficiency of up to 93.2%. • Adsorption kinetics and isotherm of the hydrogel were investigated. The hydrogel reached sorption equilibrium within 5 min, and achieved a Li+ sorption rate of 84.15%. [ABSTRACT FROM AUTHOR]

• The effect of different hollow structures on the optical absorption properties of Au nanodiscs has been studied for the first time. • The continuous sharpening of hollow negatively affects the photothermal conversion properties of Au nanodiscs. • The square hollow structure demonstrates outstanding optical absorption and efficient photothermal conversion. • This work provides valuable guidance for enhancing plasmon nanoparticles. Plasmonic nanoparticles (PNPs) with hollow structures have shown great potential for enhancing optical absorption. While spheres or cylinders are commonly used for PNPs, the study of hollow PNPs for direct absorption solar collectors is limited. This research investigates the impact of three different hollow structures (cylindrical – Case 1, square – Case 2, and trigonal – Case 3) on the optical absorption properties of Au nanodiscs. The findings demonstrate that the presence of hollow structures significantly enhances the photothermal conversion efficiency of Au nanodiscs. Specifically, Case 1, Case 2, and Case 3 exhibit photothermal conversion efficiencies that are 17.9%, 22.0%, and 16.8% higher, respectively, compared to standard Au nanodiscs. Notably, Case 2 demonstrates the highest optical absorption capacity and photothermal conversion efficiency among the three hollow structures. Through optimization, Case 2 achieves a remarkable photothermal conversion efficiency of 97.6%. Meanwhile, we also investigated the effect of continuously sharpening the hollow edges on the optical absorption properties of the nanodiscs. The continuous sharpening of the hollow core hampers both the enhancement of optical absorption properties and photothermal conversion properties in Au nanodiscs. Therefore, this research provides valuable theoretical insights for utilizing plasmonic nanoparticles with hollow structures to enhance photothermal conversion. [ABSTRACT FROM AUTHOR]

Novel nanofluids (NFs) based on bio-nanotechnology have enormous potential for solar thermal utilization. The biomimetic nanoparticles (NPs) nanostructures provide new ideas for the design of solar collector medium. Inspired by the biological properties of waxberry, we proposed waxberry-shaped biomimetic nanoparticles (WSBNPs) for solar thermal conversion in this work. Numerical results show TiN WSBNPs exhibit good optical absorption properties compared to Ag- and Au-based WSBNPs. When the volume fraction f v = 5 × 10−6 and the depth h = 15 mm, the photothermal conversion efficiency η abs can reach 93.9%. The mechanistic analysis shows that the high absorption performance of WSBNPs can be attributed to the presence of the "lightning rod" effect on the surface of NPs and the mutual coupling of surface plasmon resonance. The η abs of TiN WSBNPs can reach 90% at a lower penetration h = 11 mm and f v = 5 × 10−6. Meanwhile, the η abs of WSBNPs is proportional to the number of protrusions on the exterior surface. It has been shown that TiN WSBNPs with a raised exterior surface have excellent potential for efficient solar energy utilization. [ABSTRACT FROM AUTHOR]