Surface Engineering of Two-Dimensional Black Phosphorus for Advanced Nanophotonics.

ConspectusEverything in the world has two sides. We should correctly understand its two sides to pursue the positive side and get rid of the negative side. Recently, two-dimensional (2D) black phosphorus (BP) has received a tremendous amount of attention and has been applied for broad applications in optoelectronics, transistors, logic devices, and biomedicines due to its intrinsic properties, e.g., thickness-dependent bandgap, high mobility, highly anisotropic charge transport, and excellent biodegradability and biocompatibility. On one hand, rapid degradation of 2D BP under ambient conditions becomes a vital bottleneck that largely hampers its practical applications in optical and optoelectronic devices and photocatalysis. On the other hand, just because of its ambient instability, 2D BP as a novel kind of nanomedicine in a cancer drug delivery system can not only satisfy effective cancer therapy but also enable its safe biodegradation in vivo. Until now, a variety of surface functionality types and approaches have been employed to rationally modify 2D BP to meet the growing requirements of advanced nanophotonics.In this Account, we describe our research on surface engineering of 2D BP in two opposite ways: (i) stabilizing 2D BP by various approaches for advanced nanophotonic devices with both remarkable photoresponse behavior and environmentally structural stability and (ii) making full use of biodegradation, biocompatibility, and biological activity (e.g., photothermal therapy, photodynamic therapy, and bioimaging) of 2D BP for the construction of high-performance delivery nanoplatforms for biophotonic applications. We highlight the targeted aims of the surface-engineered 2D BP for advanced nanophotonics, including photonic devices (optics, optoelectronics, and photocatalysis) and photoinduced cancer therapy, by means of various surface functionalities, such as heteroatom incorporation, polymer functionalization, coating, heterostructure design, etc. From the viewpoint of potential applications, the fundamental properties of surface-engineered 2D BP and recent advances in surface-engineered 2D BP-based nanophotonic devices are briefly discussed. For the photonic devices, surface-engineered 2D BP can not only effectively improve environmentally structural stability but also simultaneously maintain photoresponse performance, enabling 2D BP-based devices for a wide range of practical applications. In terms of the photoinduced cancer therapy, surface-engineered 2D BP is more appropriate for the treatment of cancer due to negligible toxicity and excellent biodegradation and biocompatibility. We also provide our perspectives on future opportunities and challenges in this important and fast-growing field. It is envisioned that this Account can attract more attention in this area and inspire more scientists in a variety of research communities to accelerate the development of 2D BP for more widespread high-performance nanophotonic applications.

Phosphoric Acid-Catalyzed Alkene Difunctionalization of 2-Vinylpyridines via HOMO/LUMO Biactivated Diels-Alder Reaction.

The difunctionalization of vinylpyridines based on the cyclization strategy remains rare and underdeveloped, in contrast to the well-developed hydrogen functionalization. Current exploration on [4 + 2] cyclization of vinylpyridines mainly relies on extremely high temperatures and the LUMO activation of vinylpyridines using boron trifluoride as a strong Lewis acid. Herein, we established a phosphoric acid-catalyzed [4 + 2] cyclization reaction of 3-vinyl-1H-indoles and 2-vinylpyridines by means of the LUMO/HOMO bifunctional activation model. This protocol features mild reaction conditions, high functional group tolerance, broad substrate compatibility, and high diastereoselectivity, enabling the efficient construction of various functionalized pyridine-substituted tetrahydrocarbazoles with prominent potential in drug discovery.

Biomechanical Comparison of Different Surgical Strategies for Skip-level Cervical Degenerative Disc Disease: A Finite Element Study.

STUDY DESIGN: We constructed finite element (FE) models of the cervical spine consisting of C2-C7 and predicted the biomechanical effects of different surgical procedures and instruments on adjacent segments, internal fixation systems, and the overall cervical spine through FE analysis. OBJECTIVE: To compare the biomechanical effects between the zero-profile device and cage-plate device in skip-level multistage anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: ACDF is often considered the standard treatment for degenerative cervical spondylosis. However, the selection of surgical methods and instruments in cases of skip-level cervical degenerative disk disease is still controversial. MATERIALS AND METHODS: Three FE models were constructed, which used noncontiguous 2-level Zero-P (NCZP) devices for C3/4 and C5/6, a noncontiguous 2-level cage-plate (NCCP) for C3/4 and C5/6, and a contiguous 3-level cage-plate (CCP) for C3/6. Simulate daily activities in ABAQUS. The range of motion (ROM), von Mises stress distribution of the endplate and internal fixation system, and intervertebral disk pressure (IDP) of each model were recorded and compared. RESULTS: Similar to the stress of the cortical bone, the maximum stress of the Zero-P device was higher than that of the CP device for most activities. The ROM increments of the superior, inferior, and intermediate segments of the NCZP model were lower than those of the NCCP and CCP models in many actions. In terms of the IDP, the increment value of stress for the NCZP model was the smallest, whereas those of the NCCP and CCP models were larger. Similarly, the increment value of stress on the endplate also shows the minimum in the NCZP model. CONCLUSIONS: Noncontiguous ACDF with zero profile can reduce the stress on adjacent intervertebral disks and endplates, resulting in a reduced risk of adjacent segment disease development. However, the high cortical bone stress caused by the Zero-P device may influence the risk of fractures.

The Myb73-GDPD2-GA2ox1 transcriptional regulatory module confers phosphate deficiency tolerance in soybean.

Phosphorus is indispensable in agricultural production. An increasing food supply requires more efficient use of phosphate due to limited phosphate resources. However, how crops regulate phosphate efficiency remains largely unknown. Here, we identified a major quantitative trait locus, qPE19, that controls 7 low-phosphate (LP)-related traits in soybean (Glycine max) through linkage mapping and genome-wide association studies. We identified the gene responsible for qPE19 as GLYCEROPHOSPHORYL DIESTER PHOSPHODIESTERASE2 (GmGDPD2), and haplotype 5 represents the optimal allele favoring LP tolerance. Overexpression of GmGDPD2 significantly affects hormone signaling and improves root architecture, phosphate efficiency and yield-related traits; conversely, CRISPR/Cas9-edited plants show decreases in these traits. GmMyb73 negatively regulates GmGDPD2 by directly binding to its promoter; thus, GmMyb73 negatively regulates LP tolerance. GmGDPD2 physically interacts with GA 2-oxidase 1 (GmGA2ox1) in the plasma membrane, and overexpressing GmGA2ox1 enhances LP-associated traits, similar to GmGDPD2 overexpression. Analysis of double mutants for GmGDPD2 and GmGA2ox1 demonstrated that GmGDPD2 regulates LP tolerance likely by influencing auxin and gibberellin dose-associated cell division in the root. These results reveal a regulatory module that plays a major role in regulating LP tolerance in soybeans and is expected to be utilized to develop phosphate-efficient varieties to enhance soybean production, particularly in phosphate-deficient soils.

Improved Transcranial Plane-Wave Imaging With Learned Speed-of-Sound Maps.

Although transcranial ultrasound plane-wave imaging (PWI) has promising clinical application prospects, studies have shown that variable speed-of-sound (SoS) would seriously damage the quality of ultrasound images. The mismatch between the conventional constant velocity assumption and the actual SoS distribution leads to the general blurring of ultrasound images. The optimization scheme for reconstructing transcranial ultrasound image is often solved using iterative methods like full-waveform inversion. These iterative methods are computationally expensive and based on prior magnetic resonance imaging (MRI) or computed tomography (CT) information. In contrast, the multi-stencils fast marching (MSFM) method can produce accurate time travel maps for the skull with heterogeneous acoustic speed. In this study, we first propose a convolutional neural network (CNN) to predict SoS maps of the skull from PWI channel data. Then, use these maps to correct the travel time to reduce transcranial aberration. To validate the performance of the proposed method, numerical, phantom and intact human skull studies were conducted using a linear array transducer (L11-5v, 128 elements, pitch = 0.3 mm). Numerical simulations demonstrate that for point targets, the lateral resolution of MSFM-restored images increased by 65%, and the center position shift decreased by 89%. For the cyst targets, the eccentricity of the fitting ellipse decreased by 75%, and the center position shift decreased by 58%. In the phantom study, the lateral resolution of MSFM-restored images was increased by 49%, and the position shift was reduced by 1.72 mm. This pipeline, termed AutoSoS, thus shows the potential to correct distortions in real-time transcranial ultrasound imaging, as demonstrated by experiments on the intact human skull.