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BACKGROUND: Beamforming is vital for medical ultrasound imaging systems. The generalized sidelobe canceller (GSC) beamforming can improve the image quality of lateral resolution, but its performance improvement in contrast and robustness is limited. OBJECTIVE: This paper proposes an improved generalized sidelobe canceller algorithm based on multi-apodization with cross-correlation (MAXB-IGSC), which aims to improve the contrast and robustness of ultrasound imaging while maintaining the high image resolution and background speckle quality of GSC. METHODS: The proposed MAXB-IGSC uses multiple pairs of complementary received apodization functions to process the echo data individually to obtain multiple pairs of data sets. The average of their normalized cross-correlation coefficients is then calculated and utilized to determine the adaptive subarray length of the GSC covariance matrix and weights the output of the improved GSC. RESULTS: The MAXB-IGSC improves the contrast ratio (CR) by 171.18% in anechoic cyst simulation and by 91.23%/130.97%/171.76% in geabr_0 (a dataset from the University of Michigan) experiment compared with GSC, respectively. Furthermore, MAXB-IGSC exhibits significant noise immunity, which greatly improves the robustness of the imaging. The technology also maintains the brightness and uniformity of the background speckle. CONCLUSION: The proposed MAXB-IGSC has potential for obtaining high-quality ultrasound images in clinical applications. [ABSTRACT FROM AUTHOR]

Low‐dimensional organic–inorganic metal halides (OIMHs) have emerged as promising light emitters due to their broadband emission originating from self‐trapped excitons (STE), especially for Cu‐based OIMHs. Herein, Cu(I)‐based OIMH with a structure of (TPP)2Cu4I6·2DMSO (TPP stays for tetraphenylphosphonium, and DMSO – for dimethyl sulfoxide) has been synthesized, both in form of single crystals and as a microcrystalline powder. This compound exhibits a broadband green emission with a peak at 515 nm and a full width at half‐maximum of 78 nm, and a near‐unity photoluminescence quantum yield of 99.5%. Experimental data supported by theoretical calculations indicate that the STE emission is responsible for the green emission with a long lifetime of 2.53 µs. Down‐conversion light‐emitting device with a high luminous efficiency of 50 lm W−1 based on this compound have been fabricated, and white light has also been achieved with a high color rendering index of 96.7. Moreover, green emissive (TPP)2Cu4I6·2DMSO is utilized in scintillators for X‐ray detection and imaging, and as a luminescent ink for encryption applications. [ABSTRACT FROM AUTHOR]

In light of the economic recession in the post‐pandemic era, countries have implemented a wide array of fiscal stimulus measures as a means of addressing the prevailing economic challenges but often neglect to consider the consequences of these stimuli on the environment. Therefore, it is crucial for the government to take environmental considerations into economic stimulus packages, aiming to achieve a sustainable "green recovery." Using China's value‐added tax (VAT) reform as a quasi‐natural experiment, we find that VAT incentives have significantly improved the firm's energy efficiency through factor substitution and technological progress, indicating that tax incentives are beneficial to economic stimulus and energy saving. In addition, we find that energy market distortions play a significant negative moderating role, which weakens energy efficiency gained from the VAT incentives. Furthermore, heterogeneity analysis shows that the improvement of energy efficiency is concentrated in non‐state, high‐capital intensity, and high financing‐dependent firms. According to our findings, policymakers should have a thorough understanding of the potential of tax incentives for investment as a policy tool for achieving a "green recovery" as long as the energy market is efficient. [ABSTRACT FROM AUTHOR]

Copper-based lead-free perovskite derivatives have recently drawn great attention for their excellent optoelectronic properties and potential applications in light-emitting diodes (LEDs) and photodetectors. Herein, facile synthesis methods of cooling crystallization and wet ball milling (WBM) are adopted to synthesize K2CuCl3, resulting in single crystals (SCs) and powder samples, respectively. The as-fabricated K2CuCl3 samples exhibit blue–violet emission, with the highest photoluminescence quantum yield (PL QY) of 70% (under 280 nm excitation), and the photoluminescence (PL) is attributed to the self-trap excitons (STEs) emission. We also test the scintillation properties of K2CuCl3 for X-ray detection and imaging applications. A down-conversion LED is finally made by using K2CuCl3 as phosphor. As-synthesized K2CuCl3 can be used for either photoluminescence under UV light or X-ray imaging under X-ray radiation. -- Present in ms [ABSTRACT FROM AUTHOR]

Lead‐free vacancy‐ordered double perovskites with formula of A2M(IV)X6 have become promising alternatives to lead halide perovskites. Herein, novel direct bandgap lead‐free vacancy‐ordered double perovskites Rb2ZrCl6−xBrx (0 ≤ x ≤ 2) with highest photoluminescence quantum yield (PLQY) of 90% are synthesized by using a facile wet grinding approach. Experimental and theoretical analyses demonstrate that the bright emissions originate from the self‐trapped excitons (STEs). Additionally, thermally activated delayed fluorescence (TADF) is observed in these perovskites, confirmed by temperature‐dependent steady‐state PL spectra and time‐resolved PL spectra measurements. The competitive equilibrium relationship is demonstrated further between the singlet STEs and the triplet STEs of Rb2ZrCl6−xBrx interrelated to temperature. Meanwhile, satisfying the Vegard's law, the optical bandgap of Rb2ZrCl6−xBrx decreases linearly from 3.895 to 3.778 eV with x increasing. Furthermore, density functional theory (DFT) calculations prove the highly localized electronic states generated in flat electronic bands of Rb2ZrCl6−xBrx, as evidence by the presence of self‐trapped state in [ZrCl6−xBrx]2− octahedra, and the energy level of the halogen 3p orbitals is the key factor that dictates their bandgaps. [ABSTRACT FROM AUTHOR]