A Versatile Strategy for Concurrent Passive Daytime Radiative Cooling and Sustainable Energy Harvesting.

Developing versatile systems that can concurrently achieve energy saving and energy generation is critical to accelerate carbon neutrality. However, challenges on designing highly effective, large scale, and multifunctional photonic film hinder the concurrent combination of passive daytime radiative cooling (PDRC) and utilization of sustainable clean energies. Herein, a versatile scalable photonic film (Ecoflex@h-BN) with washable property and excellent mechanical stability is developed by combining the excellent scattering efficiency of the hexagonal boron nitride (h-BN) nanoplates with the high infrared emissivity and ideal triboelectric negative property of the Ecoflex matrix. Strikingly, sufficiently high solar reflectance (0.92) and ideal emissivity (0.97) endow the Ecoflex@h-BN film with subambient cooling effect of ≈9.5 °C at midday during the continuous outdoor measurements. In addition, the PDRC Ecoflex@h-BN film-based triboelectric nanogenerator (PDRC-TENG) exhibits a maximum peak power density of 0.5 W m-2 . By reasonable structure design, the PDRC-TENG accomplishes effective wind energy harvesting and can successfully drive the electronic device. Meanwhile, an on-skin PDRC-TENG is fabricated to harvest human motion energy and monitor moving states. This research provides a novel design of a multifunctional PDRC photonic film, and offers a versatile strategy to realize concurrent PDRC and sustainable energies harvesting.

A Novel Multifunctional Photonic Film for Colored Passive Daytime Radiative Cooling and Energy Harvesting.

Passive daytime radiative cooling (PDRC) materials with sustainable energy harvesting capability is critical to concurrently reduce traditional cooling energy utilized for thermal comfort and transfer natural clean energies into electricity. Herein, a versatile photonic film (Ecoflex@BTO@UAFL) based on a novel fluorescent luminescence color passive radiative cooling with triboelectric and piezoelectric effect is developed by filling the dielectric BaTiO3 (BTO) nanoparticles and ultraviolet absorption fluorescent luminescence (UAFL) powder into the elastic Ecoflex matrix. Test results demonstrate that the Ecoflex@BTO@UAFL photonic film exhibits a maximum passive radiative cooling effect of ∽10.1 °C in the daytime. Meanwhile, its average temperature drop in the daytime is ~4.48 °C, which is 0.91 °C higher than that of the Ecoflex@BTO photonic film (3.56 °C) due to the addition of UAFL material. Owing to the high dielectric constant and piezoelectric effect of BTO nanoparticles, the maximum power density (0.53 W m-2, 1 Hz @ 10 N) of the Ecoflex@BTO photonic film-based hybrid nanogenerator is promoted by 70.9% compared to the Ecoflex film-based TENG. This work provides an ingenious strategy for combining PDRC effects with triboelectric and piezoelectric properties, which can spontaneously achieve thermal comfort and energy conservation, offering a new insight into multifunctional energy saving.

Ultra-thin sub-diffraction metalens with a wide field-of-view for UV focusing.

In recent years, wide field-of-view imaging technology based on a metasurface has been widely applied. However, works on the reported sub-diffraction metalens with a wide field-of-view indicate that multiple structures are essential to effectively eliminate aberrations, which results in a heavy device thickness and weakens the advantage of an ultra-thin metasurface. To solve this problem, according to the super-oscillation theory and the translational symmetry of quadratic phase, as well as the principle of virtual aperture diaphragm based on wave vector filter, this Letter demonstrates a sub-diffraction metalens combined with a single quadratic metalens and a wave vector filter. Our design not only realizes the super-resolution effects of 0.74 to 0.75 times the diffraction limit in the wide field-of-view of nearly 180° for the first time to our knowledge but also compresses the device thickness to the subwavelength order in principle. The proposed ultra-thin sub-diffraction metalens with a wide field-of-view is expected to be applied in the fields of super-resolution fast scanning imaging, information detection, small target recognition, and so on.

Flexible long-wave infrared snapshot multispectral imaging with a pixel-level spectral filter array.

This paper proposes and demonstrates a flexible long-wave infrared snapshot multispectral imaging system consisting of a simple re-imaging system and a pixel-level spectral filter array. A six-band multispectral image in the spectral range of 8-12 µm with full width at half maximum of about 0.7 µm each band is acquired in the experiment. The pixel-level multispectral filter array is placed at the primary imaging plane of the re-imaging system instead of directly encapsulated on the detector chip, which diminishes the complexity of pixel-level chip packaging. Furthermore, the proposed method possesses the merit of flexible functions switching between multispectral imaging and intensity imaging by plugging and unplugging the pixel-level spectral filter array. Our approach could be viable for various practical long-wave infrared detection applications.

Simple route for high-throughput fabrication of metasurfaces using one-step UV-curable resin printing.

Phase-gradient metasurfaces are two-dimensional (2D) optical elements that can manipulate light by imposing local, space-variant phase changes on an incident electromagnetic wave. These metasurfaces hold the potential and the promise to revolutionize photonics by providing ultrathin alternatives for a wide range of common optical elements such as bulky refractive optics, waveplates, polarizers, and axicons. However, the fabrication of state-of-the-art metasurfaces typically requires some time-consuming, expensive, and possibly hazardous processing steps. To overcome these limitations on conventional metasurface fabrication, a facile methodology to produce phase-gradient metasurfaces through one-step UV-curable resin printing is developed by our research group. The method dramatically reduces the required processing time and cost, as well as eliminates safety hazards. As a proof-of-concept, the advantages of the method are clearly demonstrated via a rapid reproduction of high-performance metalenses based on the Pancharatnam-Berry phase gradient concept in the visible spectrum.

Demonstration of 120 Gbit/s turbulence-resilient coherent optical communication employing cylindrical vector beam multiplexing.

Free space optical (FSO) communication has gained widespread attention due to its advantages, including high confidentiality, high communication capacity, and no limitation of spectrum. One of the great challenges in FSO communication is the transmission performance degradation in atmospheric turbulence channel due to wavefront distortion and scintillation. Here, we proposed and experimentally demonstrated a 120 Gbit/s vector beam multiplexed coherent optical communication system with turbulence-resilient capacity. Four multiplexed vector beams, each carrying a 30 Gbit/s quadrature phase-shift keying signal, propagate through different turbulence conditions. The influence of turbulence channel on the vector beam impairments is experimentally investigated. Under the weaker turbulence conditions, the system bit error rates are below the forward error correction threshold of 3.8 × 10-3. In comparison with the Gaussian mode, the communication interruption probability of the vector beams system decreases from 36% to 12%-18% under stronger turbulence conditions.

Satellite greenness and solar-induced chlorophyll fluorescence reveal reverse desertification in Gurbantunggut Desert.

The desertification reversal is a process of revegetation and natural restoration in fragile dryland areas due to human activities and climate change mediation. Understanding the impact of desertification reversion on terrestrial ecosystems, including vegetation greenness and photosynthetic capacity, is crucial for land policy-making and carbon-cycle model improvement. However, the phenomenon of desertification reversal is rarely mentioned in previous studies, which dramatically limits the understanding of vegetation dynamics in the arid area. Therefore, it is of great necessity to investigate the status of desertification reversal on the ecosystem in arid areas. In this study, we first reported the phenomenon of desertification reversion over the southern edge of the Gurbantunggut Desert through the Moderate-resolution Imaging Spectroradiometer classification map year by year. We discussed the consequences, ways, and causes of desertification reversion. Our results showed that the desertification reversal significantly increased vegetation greenness and photosynthetic capacity, which largely offset the negative impact of desertification on the ecosystem productivity; cropland expansion and grassland's natural restoration were the two main ways of desertification reversal; the improvement of soil-water condition was an essential environmental factor leading to the phenomenon of reverse desertification. This finding highlights the importance of desertification reversal in the carbon cycle of dryland ecosystems and prove that desertification reversal is an integral part of global and dryland vegetation greening.

Surface-Initiated Synthesis of Cell-Specific Glycopolymers Using Live Mammalian Cells as Templates.

Molecular recognition is an important process in life activities where specificity is the key. However, the method to gain specificity are often complex and time-consuming. Herein, a novel, versatile, and effective way is developed to obtain cell-specific glycosurfaces by surface-initiated Cu-mediated reversible deactivation radical polymerization (Cu-RDRP) in an open to air fashion. Mammalian cells are used for the first time as live templates to realize cell-sugar monomer-aptation-polymerization which can produce cell-specific glycosurfaces. Both epithelial cell adhesion molecule (EpCAM) positive cells L929 and EpCAM negative cells Hela as models are used to acquire two cell-specific glycosurfaces, which can distinguish template-cells from others. The strategy is effective and convenient without the need of fixative pretreatment of cells. It is found that the specific capture does not rely on EpCAM antibodies, and the specificity is related to the composition and chain sequence of the glycopolymer brushes rather than surface morphology. In addition, these glycosurfaces keep the ability to identify the target cells after ten regenerative treatments, which provides another advantage for practical applications.

Thermal transport across the CoSb3-graphene interface.

CoSb3 shows intrinsically excellent electric transport performance but high thermal conductivity, resulting in low thermoelectric performance. The use of graphene to form heterogeneous interfaces shows great potential for significantly lessening the lattice thermal conductivity (κL) in CoSb3-based composites. Molecular dynamics (MD) simulations are carried out in the present work to study the interfacial thermal conductance across the CoSb3-graphene interface in the temperature range of 300 K to 800 K. The interfacial thermal conductance exhibits irregular fluctuations with temperature and CoSb3 length. Furthermore, we explored the effect of graphene layers on the interfacial heat transport of the CoSb3-graphene system. The results demonstrate that graphene layers affect the interfacial thermal conductance due to the suppression of heat flux in multilayer graphene across the c-axis. The phonon density of states (PDOS) of the CoSb3-graphene system reveals a decreased low-frequency vibration mode at 0-7 THz and an enhanced high-frequency vibration mode compared with those of CoSb3, indicating that thermal transport can be effectively suppressed by the addition of graphene.

Superhardness in nanotwinned boron carbide: a molecular dynamics study.

Boron carbide ceramics are often considered ideal materials for lightweight bulletproof armor, but their anomalous brittle failure at hypervelocity impact limits their use. Recent experiments have reported that nanotwins are ubiquitous in boron carbide and that nanotwinned samples are harder than the twin-free boron carbide, but although the strengthening effect of nanotwins on metals and alloys is well-established, their role in boron carbide ceramics is not well understood. In this study, we used classical molecular dynamics simulations to investigate how nanoscale twins affect the mechanical properties of boron carbide ceramics. Our classical molecular dynamics results show that introducing nanotwins in boron carbide can increase the shear strength limit by 19.72%, reduce the number of amorphized atoms, and narrow the width of the amorphous shear band. Under indentation load, nanotwins can also increase the compressive shear strength limit of boron carbide by 15.97% and change the crystal formation direction and region of the amorphous shear band. These findings suggest that twin boundaries can hinder the expansion of the amorphous shear band and provide a new design idea for improving the impact resistance of boron carbide ceramics and avoiding their abnormal brittle failure.

Atmospheric dryness thresholds of grassland productivity decline in China.

Atmospheric dryness events are bound to have a broad and profound impact on the functions and structures of grassland ecosystems. Current research has confirmed that atmospheric dryness is a key moisture constraint that inhibits grassland productivity, yet the risk threshold for atmospheric dryness to initiate ecosystem productivity loss has not been explored. Based on this, we used four terrestrial ecosystem models to simulate gross primary productivity (GPP) data, analyzed the role of vapor pressure deficit (VPD) in regulating interannual variability in Chinese grasslands by focusing on the dependence structure of VPD and GPP, and then constructed a bivariate linkage function to calculate the conditional probability of ecosystem GPP loss under atmospheric dryness, and further analyzed the risk threshold of ecosystem GPP loss triggered by atmospheric dryness. The main results are as follows: we found that (1) the observed and modeled VPD of Chinese grasslands increases rapidly in both historical and future periods. VPD has a strongly negative regulation on ecosystem GPP, and atmospheric dryness is an important moisture constraint that causes deficit and even death to ecosystem GPP. (2) The probability of the enhanced atmospheric dryness that induced GPP decline in Chinese grasslands in the future period increases significantly. (3) When the VPD is higher than 40.07 and 27.65 percentile of the past and future time series, respectively, the risk threshold of slight ecosystem GPP loss can be easily initiated by atmospheric dryness. (4) When the VPD is higher than 82.57 and 65.09 percentile, respectively, the threshold of moderate ecosystem GPP loss can be exceeded by the benchmark probability. (5) The risk threshold of severe ecosystem GPP loss is not initiated by atmospheric dryness in the historical period, and the threshold of severe ecosystem GPP loss can be initiated when the future VPD is higher than 91.92 percentile. In total, a slight atmospheric dryness event is required to initiate a slight ecosystem GPP loss threshold, and a stronger atmospheric dryness event is required to initiate a severe ecosystem GPP loss. Our study enhances the understandings of past and future atmospheric dryness on grassland ecosystems, and strongly suggests that more attention be invested in improving next-generation models of vegetation dynamics processes with respect to the response of mechanisms of ecosystem to atmospheric dryness.

Polarization multiplexing metasurface for dual-band achromatic focusing.

We propose a dual-band achromatic focusing metasurface based on polarization multiplexing and dispersion engineering. An anisotropic resonant phase meta-atom is designed to realize independent nonlinear phase manipulation along the orthogonal directions. Achromatic focusing metasurface and broadband reflectarray antenna are further constructed in the microwave region with a computer-assisted particle swarm optimization algorithm. The standard deviation of focus offset at 11-16 GHz (for x-polarization) and 18-24 GHz (for y-polarization) are compressed to 19.83% and 16.60% of the dispersive metasurface, respectively. The radiation gains of the reflectarray antenna increase by an average of 19.49 dB and 15.08 dB in the broadband region compared with the bare standard rectangle waveguides. Furthermore, such an achromatic metasurface can be utilized to realize different functions with polarization selectivity and applied to other frequency ranges, which holds great promise in integrated optics.

Full-space beam scanning based on transmission reflection switchable quadratic phase metasurface.

Beam scanning based on metasurfaces is widely discussed in recent years owing to its high integration, lightweight, and low cost. However, most of the reported beam scanning metasurfaces operate in either transmission or reflection mode. Here, we propose a full-space beam scanning metasurface based on transmission reflection switchable meta-atom and the quadratic phase distribution. As a validation, a metasurface array with 400 units (20 × 20) was experimentally demonstrated. Beam scanning of ± 35 ° was achieved in both transmission mode and reflection mode. A larger scanning angle (± 45 °) was further verified simulatively with a 900-units (30 × 30) array. The method provides an avenue for expanding the space of electromagnetic wave manipulation and may have great potential in wireless communication and radar detection.

Optically transparent infrared selective emitter for visible-infrared compatible camouflage.

Visible-infrared compatible camouflage is significant to enhance the equipment survivability through counteracting the modern detecting and surveillance systems. However, there are still great challenges in simultaneously achieving multispectral camouflage with high transmittance in visible, low emissivity in the atmospheric windows and high emissivity in the non-atmospheric window, which can be attributed to the mutual influence and restriction within these characteristics. Here, we proposed an optically transparent infrared selective emitter (OTISE) composed of three Ag-ZnO-Ag disk sub-cells with anti-reflection layers, which can synchronously improve the visible transmittance and widen absorption bandwidth in the non-atmospheric window by enhancing and merging resonance response of multi-resonators. Test results reveal that low emissivity in infrared atmospheric windows, high emissivity in the 5-8 µm non-atmospheric window and high optical transparency have been obtained. In addition, the radiative flux of OTISE in 3-5 µm and 8-14 µm are respectively 34.2% and 9.3% of that of blackbody and the energy dissipation of OTISE is 117% of that of chromium film. Meanwhile, it keeps good optical transparency due to the ultrathin Ag film. This work provides a novel strategy to design the optically transparent selective emissive materials, implying a promising application potential in visible and infrared camouflage technology.

Volumetric apparent diffusion coefficient (ADC) histogram metrics as imaging biomarkers for pretreatment predicting response to fertility-sparing treatment in patients with endometrial cancer.

OBJECTIVES: To investigate the feasibility of volumetric apparent diffusion coefficient (ADC) histogram analysis for prediction of fertility-sparing treatment (FST) response in patients with endometrial cancer (EC). METHODS: Pretreatment data of 54 EC patients with FST were retrospectively analyzed. Treatment response at each follow-up was pathologically evaluated. The associations of ADC histogram metrics (volume, minADC, maxADC, meanADC; 10th, 25th, 50th, 75th and 90th ADC percentiles; skewness; kurtosis) and baseline clinical characteristics with complete response (CR) at the second and third follow-ups, two-consecutive CR, and recurrence at the final follow-up were evaluated by uni- and multivariable logistic regression analysis. Receiver operating characteristic (ROC) curve analysis was used for diagnostic performance evaluation. RESULTS: Compared with non-CR patients, CR patients had significantly higher minADC and 10th and 25th ADC percentiles at the second follow-up (P = 0.008, 0.039, and 0.034, respectively) and higher minADC, older age, lower HE4 level, and higher overweight rate at the third follow-up (P = 0.001, 0.040, 0.021, and 0.004, respectively). Patients with two-consecutive CR had a significantly higher minADC than those without (P = 0.018). There was no association between ADC metrics or clinical characteristics and recurrence (all P > 0.05). MinADC yielded the largest AUC in predicting CR (0.688 and 0.735 at the second and third follow-up, respectively) and the presence of two-consecutive CR (0.753). When combined with patient age and HE4 level, the prediction of CR could be further improved at the third follow-up, with an AUC of 0.786. CONCLUSION: Pretreatment minADC could be a potential imaging biomarker for predicting FST response. Clinical characteristics may have incremental value to minADC in predicting CR.

Volumetric ADC histogram analysis for preoperative evaluation of LVSI status in stage I endometrioid adenocarcinoma.

OBJECTIVES: To investigate the value of volumetric ADC histogram metrics for evaluating lymphovascular space invasion (LVSI) status in stage I endometrioid adenocarcinoma (EAC). METHODS: Preoperative MRI of 227 patients with stage I EAC were retrospectively analyzed. ADC histogram data were derived from the whole tumor with ROIs drawn on all slices of DWI scans (b = 0, 1000 s/mm2). The Student t-test was performed to compare ADC histogram metrics (minADC, maxADC, and meanADC; 10th, 25th, 50th, 75th, and 90th percentiles of ADC; skewness; and kurtosis) between the LVSI-positive and LVSI-negative groups, as well as between stage Ia and Ib EACs. ROC curve analysis was carried out to evaluate the diagnostic performance of ADC histogram metrics in predicting LVSI status in EAC. RESULTS: The minADC and meanADC and 10th, 25th, 50th, 75th, and 90th percentiles of ADC were significantly lower in LVSI-positive EACs compared with those in the LVSI-negative groups for stage I, Ia, and Ib EACs (all p < 0.05). MeanADC ≤ 0.857 × 10-3 mm2/s, meanADC ≤ 0.854 × 10-3 mm2/s, and the 90th percentile of ADC ≤ 1.06 × 10-3 mm2/s yielded the largest AUC of 0.844, 0.844, and 0.849 for evaluating LVSI positivity in stage I, Ia, and Ib tumors, respectively, with sensitivity of 75.4%, 75.0%, and 76.2%; specificity of 80.0%, 83.1%, and 82.1%; and accuracy of 79.3%, 81.5%, and 79.6%, respectively. CONCLUSION: Volumetric ADC histogram metrics might be helpful for the preoperative evaluation of LVSI status and personalized clinical management in patients with stage I EAC. KEY POINTS: • Volumetric ADC histogram analysis helps evaluate LVSI status preoperatively. • LVSI-positive EAC is associated with a reduction in multiple volumetric ADC histogram metrics. • MeanADC and the 90th percentile of ADC were shown to be best in evaluating LVSI- positivity in stage Ia and Ib EACs, respectively.

Interannual variability in summer climate change controls GPP long-term changes.

Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with implications for the functioning of the Earth system and the provision of ecosystem services. How vegetation responds to a changing environment is an important scientific issue, but there is a lack of coverage of the relative contributions that long-term variation and interannual variability in vegetation across seasons play in ecosystem response to global change. Here, we used four terrestrial ecosystem models provided by MsTMIP to examine four key environmental drivers of gross primary productivity (GPP) change over the period 1901-2010. Our findings showed that (1) for all seasons, interannual variability in climate change are the main environmental factor controlling seasonal GPP variability. (2) Summer is the key season controlling the variation of annual GPP, and its long-term trend and interannual variability can explain 61.50% of the variation of grassland GPP in China. (3) Interannual variability in summer climate change exceeded the CO2 fertilization effect and nitrogen deposition as the controlling component (more than 40%) of long-term variation in Chinese grassland GPP. These studies highlight the important role of interannual variability in climate in reshaping the seasonality of vegetation growth, and will provide a precursor to future environmental drivers that can be precisely attributed to global vegetation change.

Whole-tumor histogram analysis of apparent diffusion coefficient for differentiating adenosquamous carcinoma and adenocarcinoma from squamous cell carcinoma in patients with cervical cancer.

BACKGROUND: Differentiating adenosquamous carcinoma (ASC) and adenocarcinoma (AC) from squamous cell carcinoma (SCC) precisely is crucial for treatment strategy and prognosis prediction in patients with cervical cancer (CC). PURPOSE: To differentiate ASC and AC from SCC in patients with CC using the apparent diffusion coefficient (ADC) histogram analysis. MATERIAL AND METHODS: A total of 118 patients with histologically diagnosed ASC, AC, and SCC were included. The ADC histogram parameters were extracted from ADC maps. Receiver operating characteristic analysis was performed to evaluate the diagnostic performance of each ADC histogram parameter in differentiating the subtypes of CC. The predictors for histologic subtypes were further selected using univariate and multivariate logistic regression analyses. RESULTS: The ADCmean, ADCmax, ADCP10, ADCP25, ADCP75, ADCP90, ADCmedian, and ADCmode of the ASC were significantly lower than those of the AC; and ADCkurtosis and ADCskewness of the ASC were lower than those of the SCC. The ADCmean, ADCmax, ADCP10, ADCP25, ADCP75, ADCP90, ADCmedian, and ADCmode of AC were significantly higher than those of the SCC. The ADCP10 and ADCP10 + diameter yielded the AUCs of 0.753 and 0.778 in differentiating ASC from AC. The ADCmedian and ADCmedian + diameter yielded the AUCs of 0.807 and 0.838 in differentiating AC from SCC. The ADCskewness yielded the AUC of 0.713 in differentiating ASC from SCC. CONCLUSION: The ADCP10 and ADCP10 + diameter, ADCmedian, and ADCmedian + diameter performed well in differentiating ASC from AC and AC from SCC, respectively. However, ADCskewness exhibited a limited ability in differentiating ASC from SCC.

Polarization-dependent spatial channel multiplexing dynamic hologram in the visible band.

In this work, we propose dynamic holography based on metasurfaces combining spatial channel multiplexing and polarization multiplexing. In this design, spatial channels can provide up to 3N holographic frames, which not only increase the possibility of dynamic control but also increase the privacy of the holographic display. This design is also sensitive to polarization, so it further expands the spatial channel capacity. For the left and right circular polarization incident light, there are different dynamic pixel schemes. Therefore, this approach holds promise in the holographic display, optical storage, optics communication, optical encryption, and information processing.

Broadband achromatic metasurfaces for sub-diffraction focusing in the visible.

Conventional achromatic optical systems are matured to achieve effective chromatic aberration correction and diffraction-limited resolution by the multiple bulky lenses. The emergence of the super-oscillation phenomenon provides an effective method for non-invasive far-field super-resolution imaging. Nevertheless, most super-oscillatory lenses are significantly restricted by the chromatic aberration due to the reliance on delicate interference; on the other hand, most achromatic lenses cannot break the diffraction limit. In this article, a single-layer broadband achromatic metasurface comprising sub-wavelength anisotropic nanostructures has been proposed to achieve sub-diffraction focusing with a focal length of f=60 µm and a diameter of 20 µm in the visible ranging from 400 nm to 700 nm, which are capable of generating sub-diffraction focal spots under the left-handed circularly polarized incident light with arbitrary wavelength in the working bandwidth at the same focal plane. This method may find promising potentials in various applications such as super-resolution color imaging, light field cameras, and machine vision.