Cervical lymph node metastasis prediction from papillary thyroid carcinoma US videos: a prospective multicenter study.

BACKGROUND: Prediction of lymph node metastasis (LNM) is critical for individualized management of papillary thyroid carcinoma (PTC) patients to avoid unnecessary overtreatment as well as undesired under-treatment. Artificial intelligence (AI) trained by thyroid ultrasound (US) may improve prediction performance. METHODS: From September 2017 to December 2018, patients with suspicious PTC from the first medical center of the Chinese PLA general hospital were retrospectively enrolled to pre-train the multi-scale, multi-frame, and dual-direction deep learning (MMD-DL) model. From January 2019 to July 2021, PTC patients from four different centers were prospectively enrolled to fine-tune and independently validate MMD-DL. Its diagnostic performance and auxiliary effect on radiologists were analyzed in terms of receiver operating characteristic (ROC) curves, areas under the ROC curve (AUC), accuracy, sensitivity, and specificity. RESULTS: In total, 488 PTC patients were enrolled in the pre-training cohort, and 218 PTC patients were included for model fine-tuning (n = 109), internal test (n = 39), and external validation (n = 70). Diagnostic performances of MMD-DL achieved AUCs of 0.85 (95% CI: 0.73, 0.97) and 0.81 (95% CI: 0.73, 0.89) in the test and validation cohorts, respectively, and US radiologists significantly improved their average diagnostic accuracy (57% vs. 60%, P = 0.001) and sensitivity (62% vs. 65%, P < 0.001) by using the AI model for assistance. CONCLUSIONS: The AI model using US videos can provide accurate and reproducible prediction of cervical lymph node metastasis in papillary thyroid carcinoma patients preoperatively, and it can be used as an effective assisting tool to improve diagnostic performance of US radiologists. TRIAL REGISTRATION: We registered on the Chinese Clinical Trial Registry website with the number ChiCTR1900025592.

Strain-Driven Solid-Solid Crystal Conversion in Chiral Hybrid Pseudo-Perovskites with Paramagnetic-to-Ferromagnetic Transition.

Hybrid organic-inorganic perovskites (HOIPs) are promising stimuli-responsive materials (SPMs) owing to their molecular softness and tailorable structural dimensionality. The design of mechanically responsive HOIPs requires an in-depth understanding of how lattice strain induces intermolecular rearrangement that impacts physical properties. While chirality transfer from an organic cation to an inorganic lattice is known to influence chiral-optical properties, its effect on strain-induced phase conversion has not been explored. As opposed to achiral or racemic organic cations, chiral organic cations can potentially afford a new dimension in strain-responsive structural change. Herein, we demonstrate that mechanical strain induces a solid phase crystal conversion in chiral halide pseudo-perovskite single crystals (R/S)-(FE)2CuCl4 (FE = (4-Fluorophenyl)ethylamine) from a 0D isolated CuCl4 tetrahedral to 1D corner-sharing CuFCl5 octahedral framework via the incorporation of Cu···F interaction and N-H···F hydrogen bonding. This strain-induced crystal-to-crystal conversion involves the connection of neighboring 0D CuCl4 tetrahedra via Cu2+-Cl--Cu2+ linkages as well as the incorporation of a F-terminated organic cation as one of the X atoms in BX6 octahedra, leading to a reduced band gap and paramagnetic-to-ferromagnetic conversion. Control experiments using nonchiral or racemic perovskite analogs show the absence of such solid phase conversion. To demonstrate pressure-sensitive properties, the 0D phase is dispersed in water-soluble poly(vinyl alcohol) (PVA) polymer, which can be applied to a large-scale pressure-induced array display on fibrous Spandex substrates via a screen-printing method.

Near-90° Switch in the Polar Axis of Dion-Jacobson Perovskites by Halide Substitution.

Ferroelectricity in two-dimensional hybrid (2D) organic-inorganic perovskites (HOIPs) can be engineered by tuning the chemical composition of the organic or inorganic components to lower the structural symmetry and order-disorder phase change. Less efforts are made toward understanding how the direction of the polar axis is affected by the chemical structure, which directly impacts the anisotropic charge order and nonlinear optical response. To date, the reported ferroelectric 2D Dion-Jacobson (DJ) [PbI4]2- perovskites exhibit exclusively out-of-plane polarization. Here, we discover that the polar axis in ferroelectric 2D Dion-Jacobson (DJ) perovskites can be tuned from the out-of-plane (OOP) to the in-plane (IP) direction by substituting the iodide with bromide in the lead halide layer. The spatial symmetry of the nonlinear optical response in bromide and iodide DJ perovskites was probed by polarized second harmonic generation (SHG). Density functional theory calculations revealed that the switching of the polar axis, synonymous with the change in the orientation of the sum of the dipole moments (DMs) of organic cations, is caused by the conformation change of organic cations induced by halide substitution.

Electron Spin Decoherence Dynamics in Magnetic Manganese Hybrid Organic-Inorganic Crystals: The Effect of Lattice Dimensionality.

Organic-inorganic metal hybrids with their tailorable lattice dimensionality and intrinsic spin-splitting properties are interesting material platforms for spintronic applications. While the spin decoherence process is extensively studied in lead- and tin-based hybrids, these systems generally show short spin decoherence lifetimes, and their correlation with the lattice framework is still not well-understood. Herein, we synthesized magnetic manganese hybrid single crystals of (4-fluorobenzylamine)2MnCl4, ((R)-3-fluoropyrrolidinium)MnCl3, and (pyrrolidinium)2MnCl4, which represent a change in lattice dimensionality from 2D and 1D to 0D, and studied their spin decoherence processes using continuous-wave electron spin resonance spectroscopy. All manganese hybrids exhibit nanosecond-scale spin decoherence time τ2 dominated by the symmetry-directed spin exchange interaction strengths of Mn2+-Mn2+ pairs, which is much longer than lead- and tin-based metal hybrids. In contrast to the similar temperature variation laws of τ2 in 2D and 0D structures, which first increase and gradually drop afterward, the 1D structure presents a monotonous rise of τ2 with the temperatures, indicating the strong correlation of spin decoherence with the lattice rigidity of the inorganic framework. This is also rationalized on the basis that the spin decoherence is governed by the competitive contributions from motional narrowing (prolonging the τ2) and electron-phonon coupling interaction (shortening the τ2), both of which are thermally activated, with the difference that the former is more pronounced in rigid crystalline lattices.

Module-Patterned Polymerization towards Crystalline 2D sp2 -Carbon Covalent Organic Framework Semiconductors.

Despite rapid progress over the past decade, most polycondensation systems even upon a small structural variation of the building units eventually result in amorphous polymers other than the desired crystalline covalent organic frameworks. This synthetic dilemma is a central and challenging issue of the field. Here we report a novel approach based on module-patterned polymerization to enable efficient and designed synthesis of crystalline porous polymeric frameworks. This strategy features a wide applicability to allow the use of various knots of different structures, enables polycondensation with diverse linkers, and develops a diversity of novel crystalline 2D polymers and frameworks, as demonstrated by using the C=C bond-formation polycondensation reaction. The new sp2 -carbon frameworks are highly emissive and enable up-conversion luminescence, offer low band gap semiconductors with tunable band structures, and achieve ultrahigh charge mobilities close to theoretically predicted maxima.

Single-particle studies on plasmon enhanced photoluminescence of monolayer MoS2 by gold nanoparticles of different shapes.

Plasmon-exciton interactions between noble metal nanostructures and two-dimensional transition metal dichalcogenides have drawn great interest due to their significantly enhanced optical properties. Plasmon resonance of noble metal nanoparticles and plasmon-exciton interactions are strongly dependent on the particle morphology. Single-particle spectroscopic studies can overcome the ensemble average effects of sample inhomogeneity to unambiguously reveal the effects of the particle morphology. In this work, plasmon modulated emission of MoS2 in various plasmon-MoS2 hybrid structures has been studied on the single-particle level. Gold (Au) nanoantennas of different shapes including nanosphere, nanorod, nanocube, and nanotriangle with similar overall dimensions, which have different sharp tips and contact areas with MoS2, have been chosen to explore the particle shape effects. Different extent of enhancement in photoluminescence (PL) of MoS2 was observed for Au nanoantennas of different shapes. It was found that Au nanotriangles gave the highest enhancement factor, while Au nanospheres gave the lowest enhancement factor. The numerical simulation results show that the dominant contribution arises from an increased quantum yield, while enhanced excitation efficiency just plays a minor role. The quantum yield enhancement is affected by both the sharp tips and contact mode of the Au nanoantenna with MoS2. Polarization of the MoS2 emission was also found to be modulated by the plasmon mode of the Au nanoantenna. These single-particle spectroscopic studies allow us to unambiguously reveal the effects of the particle morphology on plasmon enhanced PL in these nanohybrids to provide a better understanding of the plasmon-exciton interactions.

Self-Powered Photodetector Using Two-Dimensional Ferroelectric Dion-Jacobson Hybrid Perovskites.

Dion-Jacobson (DJ) phase organic-inorganic hybrid perovskites (OIHPs) have emerged as promising alternatives to Ruddlesden-Poppers perovskites because of their chemical stability and ferroelectric phase. Here we fabricate a ferroelectricity-modulated photodetector based on the n = 2 homologue of the ferroelectric two-dimensional DJ-OIHP (AMP)(MA)Pb2I7 (DJPn=2, AMP = 4-(aminomethyl)piperidinium; MA = methylammonium), which shows an out-of-plane polarization and a saturated polarization (Ps) value of 3.7 µC/cm2. The coercive field of DJPn=2 (0.34 kV/cm) is lower than that for the n = 1 homologue (AMP)PbI4 (DJPn=1,0.4 kV/cm). DJPn=2 has a much longer carrier lifetime and absorption edge (580 nm, 2.13 eV) in comparison to DJPn=1 (523 nm, 2.37 eV); thus, DJPn=2 can be used for efficient photodetection in the visible range, in which a responsivity of 0.16 mA/W was achieved at 532 nm. The influence of remnant polarization on the direction and magnitude of the photocurrent was also demonstrated.

Aggregation-Induced Plasmon Coupling-Enhanced One- and Two-Photon Excitation Fluorescence by Silver Nanoparticles.

Plasmon coupling-induced intense local electrical field in the gap of closely packed metal nanoparticles (NPs) has been known capable of significantly enhancing optical properties of chromophores. Here, we have investigated aggregation-induced plasmon coupling-enhanced one-photon excitation (1PE) and two-photon excitation (2PE) fluorescence of dyes using Ag NPs of three different sizes (20, 36, and 48 nm). The fluorescence of a model dye, Rhodamine B isothiocyanate (RiTC), was prequenched by attaching to Ag NPs and subsequently enhanced upon forming aggregates of Ag NPs. It was found that aggregates of larger sized Ag NPs gave larger 1PE and 2PE fluorescence enhancement on the basis of free dyes, while aggregates of smaller counterparts displayed larger enhancement on the basis of the corresponding prequenched ones. 1PE and 2PE fluorescence were enhanced by 2.5- and 10.2-fold by aggregated 48 nm Ag NPs compared to free dyes and by 8.0- and 22.5-fold by aggregated 20 nm Ag NPs compared to the quenched ones, respectively. This scheme achieved fluorescence enhancement significantly beyond the level of fluorescence recovery, much larger than conventional turn-on fluorescence probes, which is attractive for developing sensitive fluorescence turn-on-based detection with reduced background.

Expression of CCL-18 and CX3CL1 in Serum, and Their Potential Roles as Two Diagnostic and Prognostic Markers in Chronic Obstructive Pulmonary Disease and Chronic cor Pulmonale (COPD&CCP): a Pilot Study.

BACKGROUND: CC chemokine ligand-18 (CCL-18) and CX3 chemokine ligand 1 (CX3CL1) are key factors of vascular and tissue injury in chronic respiratory diseases. Here, we investigated the value of CCL-18 and CX3CL1 in diagnosis and prognosis of patients with chronic obstructive pulmonary disease and chronic cor pulmonale (COPD&CCP). METHODS: First, we investigated the expression profile of CCL-18 and CX3CL1 in serum of COPD&CCP patients. Then the relationship of the level of CCL-18 and CX3CL1 with clinicopathological characteristics was analyzed. Subsequently, we evaluated the diagnostic accuracy of CCL-18 and CX3CL1 to discriminate COPD&CCP. The prognostic value and therapy outcome were also evaluated. RESULTS: Compared to healthy subjects, the level of CCL-18 (8.01 ± 2.01 ng/mL) and CX3CL1 (2,096.11 ± 306.09 ng/mL) was significantly increased in COPD&CCP patients (p < 0.05). The upregulation of CCL-18 and CX3CL1 was significantly correlated with clinicopathological characteristics including CRP, IL-6, FIB, NT-proBNP, FEV1, FEV1/FVC, PASP, LVEF, and T wave anomaly. The combination of CCL-18 and CX3CL1 showed high precision for discriminating COPD&CCP with high AUC values (0.828), sensitivity (66.1%), and specificity (92.5%). Furthermore, CCL-18 and CX3CL1 acted as independent factors which lead to poor clinical benefits and indicated poor prognosis of COPD&CCP patients. CONCLUSIONS: Taken together, our results indicated that CCL-18 and CX3CL1 could act as suitable biomarkers in prognosis and prognostic evaluation of COPD&CCP.

Gate-Tunable In-Plane Ferroelectricity in Few-Layer SnS.

Ultrathin ferroelectrics hold great promise for modern miniaturized sensors, memories, and optoelectronic devices. However, in most ferroelectric materials, polarization is destabilized in ultrathin films by the intrinsic depolarization field. Here we report robust in-plane ferroelectricity in few-layer tin sulfide (SnS) 2D crystals that is coupled anisotropically to lattice strain. Specifically, the intrinsic polarization of SnS manifests as nanoripples along the armchair direction due to a converse piezoelectric effect. Most interestingly, such nanoripples show an odd-and-even effect in terms of its layer dependence, indicating that it is highly sensitive to changes in inversion symmetry. Ferroelectric switching is demonstrated in field-effect transistor devices fabricated on ultrathin SnS films, in which a stronger ferroelectric response is achieved at negative gate voltages. Our work shows the promise of 2D SnS in ultrathin ferroelectric field-effect transistors as well as nanoscale electromechanical systems.

Giant Enhancement of Second Harmonic Generation Accompanied by the Structural Transformation of 7-Fold to 8-Fold Interpenetrated Metal-Organic Frameworks (MOFs).

Interpenetration in metal-organic frameworks (MOFs) is an intriguing phenomenon with significant impacts on their properties, and functional applications. Herein, we show that a 7-fold interpenetrated MOF (1) is transformed into an 8-fold interpenetrated MOF by the loss of DMF in a single-crystal-to-single-crystal manner. This is accompanied by a giant enhancement of the second harmonic generation (SHG ca. 125 times) and two-photon photoluminescence (ca. 14 times). The strengthened π-π interaction between the individual diamondoid networks and intensified oscillator strength of the molecules aid the augment of dipole moments and boost the nonlinear optical conversion efficiency. Large positive and negative thermal expansions of 1 occur at 30-150 °C before the loss of DMF. These results offer an avenue to manipulate the NLO properties of MOFs using interpenetration and provide access to tunable single-crystal NLO devices.

Giant Emission Enhancement of Solid-State Gold Nanoclusters by Surface Engineering.

Ligand-induced surface restructuring with heteroatomic doping is used to precisely modify the surface of a prototypical [Au25 (SR1 )18 ]- cluster (1) while maintaining its icosahedral Au13 core for the synthesis of a new bimetallic [Au19 Cd3 (SR2 )18 ]- cluster (2). Single-crystal X-ray diffraction studies reveal that six bidentate Au2 (SR1 )3 motifs (L2) attached to the Au13 core of 1 were replaced by three quadridentate Au2 Cd(SR2 )6 motifs (L4) to create a bimetallic cluster 2. Experimental and theoretical results demonstrate a stronger electronic interaction between the surface motifs (Au2 Cd(SR2 )6 ) and the Au13 core, attributed to a more compact cluster structure and a larger energy gap of 2 compared to that of 1. These factors dramatically enhance the photoluminescence quantum efficiency and lifetime of crystal of the cluster 2. This work provides a new route for the design of a wide range of bimetallic/alloy metal nanoclusters with superior optoelectronic properties and functionality.

Ferroelectricity and Rashba Effect in a Two-Dimensional Dion-Jacobson Hybrid Organic-Inorganic Perovskite.

Hybrid organic-inorganic perovskites (HOIPs) are a new generation of high-performance materials for solar cells and light emitting diodes. Beyond these applications, ferroelectricity and spin-related properties of HOIPs are increasingly attracting interests. The presence of strong spin-orbit coupling, allied with symmetry breaking ensured by remanent polarization, should give rise to Rashba-type splitting of electronic bands in HOIP. However, the report of both ferroelectricity and Rashba effect in HOIP is rare. Here we report the observation of robust ferroelectricity and Rashba effect in two-dimensional Dion-Jacobson perovskites.

Molecularly thin two-dimensional hybrid perovskites with tunable optoelectronic properties due to reversible surface relaxation.

Due to their layered structure, two-dimensional Ruddlesden-Popper perovskites (RPPs), composed of multiple organic/inorganic quantum wells, can in principle be exfoliated down to few and single layers. These molecularly thin layers are expected to present unique properties with respect to the bulk counterpart, due to increased lattice deformations caused by interface strain. Here, we have synthesized centimetre-sized, pure-phase single-crystal RPP perovskites (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 (n = 1-4) from which single quantum well layers have been exfoliated. We observed a reversible shift in excitonic energies induced by laser annealing on exfoliated layers encapsulated by hexagonal boron nitride. Moreover, a highly efficient photodetector was fabricated using a molecularly thin n = 4 RPP crystal, showing a photogain of 105 and an internal quantum efficiency of ~34%. Our results suggest that, thanks to their dynamic structure, atomically thin perovskites enable an additional degree of control for the bandgap engineering of these materials.

Vapour-liquid-solid growth of monolayer MoS2 nanoribbons.

Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour-solid-solid mode. Here, we report the vapour-liquid-solid growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour-liquid-solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the 'crawling mode' when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H- or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nanostructure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.

The role of gibberellin synthase gene GhGA2ox1 in upland cotton (Gossypium hirsutum L.) responses to drought and salt stress.

Gibberellins (GAs) is one kind of important endogenous hormone in plants that regulates vegetative and reproductive growth of plants. GA2ox is a class of oxidase that plays a regulatory role in the third stage of GAs synthesis. In this paper, we cloned the GhGA2ox1 gene from an upland cotton (Gossypium hirsutum L. var. CCRI49). The results showed that the CDS of GhGA2ox1 is 996 bp, which encode 331 amino acids, which has high homology with GhGA2ox2 and NtGA2ox1. The quantitative real-time PCR showed that under the conditions of salt and drought stress, the expression of GhGA2ox1 had a higher upregulation in root, stem, and leaf of transgenic plant, compared with non-transgenic plant. Cotton plant that overexpressed the GhGA2ox1 gene showed higher drought and salt tolerance than non-transgenic cotton plant, and these results were supported by data of higher free proline, chlorophyll, and relative water content in transgenic plant compared with control plant. The expression level of antiretroviral genes, including GhEREB2, GhDREB1, GhWRKY5, and GhP5CS, was upregulated to varying degrees in transgenic plant. The above results indicate that overexpressed GhGA2ox1 gene can increases the tolerance to respond to drought and salt stress in upland cotton.

Disorder Engineering in Monolayer Nanosheets Enabling Photothermic Catalysis for Full Solar Spectrum (250-2500†nm) Harvesting.

A persistent challenge in classical photocatalyst systems with extended light absorption is the unavoidable trade-off between maximizing light harvesting and sustaining high photoredox capability. Alternatively, cooperative energy conversion through photothermic activation and photocatalytic redox is a promising yet unmet scientific proposition that critically demands a spectrum-tailored catalyst system. Here, we construct a solar thermal-promoted photocatalyst, an ultrathin "biphasic" ordered-disordered D-HNb3 O8 junction, which performs two disparate spectral selective functions of photoexcitation by ordered structure and thermal activated conversion via disordered lattice for combinatorial photothermal mediated catalysis. This in situ synthetically immobilized lattice distortion, constrained to a single-entity monolayer structure not only circumvents interfacial incompatibility but also triggers near-field temperature rise at the catalyst-reactant complexes' proximity to promote photoreaction. Ultimately, a generic full solar conversion improvement for H2 fuel production, organic transformation and water purification is realized.

Ultrafast carrier dynamics and third-order nonlinear optical properties of AgInS2/ZnS nanocrystals.

Broad photoluminescence (PL) emission, a large Stokes shift and extremely long-lived radiative lifetimes are the characteristics of ternary I-III-VI semiconductor nanocrystals (NCs), such as CuInS2 and AgInS2. However, the lack of understanding regarding the intriguing PL mechanisms and photo-carrier dynamics limits their further applications. Here, AgInS2 and AgInS2/ZnS NCs were chemically synthesized and their carrier dynamics were studied by time-resolved PL spectroscopy. The results demonstrated that the surface defect state, which contributed dominantly to the non-radiative decay processes, was effectively passivated through ZnS alloying. Femtosecond transient absorption spectroscopy was also used to investigate the carrier dynamics, revealing the electron storage at the surface state and donor state. Furthermore, the two photon absorption properties of AgInS2 and AgInS2/ZnS NCs were measured using an open-aperture Z-scan technique. The improved third-order nonlinear susceptibility [Formula: see text] of AgInS2 through ZnS alloying demonstrates potential application in two photon PL biological imaging.

Photoinduced Nickel-Catalyzed Chemo- and Regioselective Hydroalkylation of Internal Alkynes with Ether and Amide α-Hetero C(sp3)-H Bonds.

A direct hydroalkylation of disubstituted alkynes with unfunctionalized ethers and amides was achieved in an atom-efficient and additive-free manner through the synergistic combination of photoredox and nickel catalysis. The protocol was effective with a wide range of internal alkynes, providing products in a highly selective fashion. Notably, the observed regioselectivity is complementary to conventional radical addition processes. Mechanistic investigations suggest that the photoexcited iridium catalyst facilitated the nickel activation via single-electron transfer.

Au-Ag core-shell nanoparticles for simultaneous bacterial imaging and synergistic antibacterial activity.

Au@Ag nanoparticles (NPs) were recently found to display giant two-photon photoluminescence (2PPL) enhancement, with an enhancement factor up to 815 fold upon aggregate formation. Based on this finding, two-photon imaging of bacteria by Au@Ag NPs under near-infrared (NIR) femtosecond laser pulses was demonstrated in this study, as positively charged Au@Ag NPs can form aggregates on the negatively charged bacterial surface, yielding strong 2PPL emission. The aggregation-enhanced 2PPL of Au@Ag NPs stemmed from higher two-photon excitation efficiency, implying strong two-photon photothermal effects. Au@Ag NPs showed strong antibacterial activity (minimum inhibition concentration as low as 7.5pM against Staphylococcus aureus) and negligible toxicity to human dermal fibroblasts. Their bactericidal activity was further enhanced under NIR irradiation due to strong two-photon photothermal effects. Au@Ag NPs effectively removed 85% of the notorious bacterial biofilm within 4 min under NIR irradiation. These Au@Ag NPs can potentially be used as imaging and antibacterial agents.