Fluctuation-enhanced Kerr nonlinearity in an atom-assisted optomechanical system with atom-cavity interactions.

We examine the effect of cavity field fluctuations on Kerr nonlinearity in an atom-assisted optomechanical system. It is found that a new self-Kerr (SK) nonlinearity term, which can greatly surpass that of a classical Λ type atomic system when the hybrid system has numerous atoms, is generated based on cavity field fluctuations by atom-cavity interactions. A strong photon-phonon cross-Kerr (CK) nonlinearity is also produced based on cavity field fluctuations. These nonlinearity features can be modified by atom-cavity and optomechanical interactions. This work may provide a new method to enhance the SK nonlinearity and generate the photon-phonon CK nonlinearity.

An MRI-based radiomics signature as a pretreatment noninvasive predictor of overall survival and chemotherapeutic benefits in lower-grade gliomas.

OBJECTIVES: The aim of this study was to develop and validate a radiomics signature for predicting survival and chemotherapeutic benefits of patients with lower-grade gliomas (LGG). METHODS: Radiomics features were extracted from precontrast axial fluid-attenuated inversion recovery (FLAIR) and contrast-enhanced axial T-1 weighted (CE-T1-w) sequence. Lasso Cox regression model was used for feature selection and radiomics signature building. The radiomics signature was developed in a primary cohort that consisted of 149 LGG patients and was then validated on an entirely new validation cohort that contained 66 LGG patients. A radiomics nomogram for the prediction of OS was established by adding the radiomics to clinicopathologic nomogram which developed with clinical data. RESULTS: A radiomics signature derived from joint CE-T1-w and FLAIR images showed better prognostic performance (C-index, 0.798) than signatures derived from CE-T1-w (C-index, 0.744) or FLAIR (C-index, 0.736) sequences alone. Multivariable Cox regression revealed that the radiomics signature was an independent prognostic factor. One radiomics nomogram integrated the radiomics signature from joint CE-T1-w and FLAIR sequences with the clinicopathologic nomogram outperformed the clinicopathologic nomogram based on clinicopathologic data alone in predicting OS of LGG (C-index, 0.821 vs. 0.692; p < 0.001). Further analysis revealed that patients with higher radiomics signature were prone to benefit from chemotherapy. CONCLUSIONS: The radiomics signature was independent with clinicopathologic data and was a noninvasive pretreatment predictor for LGG patients' survival. Moreover, it could predict which patients with LGG benefit from chemotherapy. KEY POINTS: • A radiomics signature derived from joint CE-T1-w and FLAIR sequences showed better prognostic performance than signatures derived from either single imaging modality. • The radiomics signature is an independent prognostic factor and outperformed clinicopathologic features in predicting overall survival of LGG patients. • The radiomics signature could help preoperatively identify LGG patients who may benefit from chemotherapy.

Tightly-bound trion and bandgap engineering viaγ-ray irradiation in the monolayer transition metal dichalcogenide WSe2.

Afterγ-ray irradiation treatment, a monolayer tungsten diselenide could be transitioned into an n-doped semiconductor due to the anion vacancies created by the radiation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interface. Change in the lattice vibrational modes induced by passivation of oxygen is captured by Raman spectroscopy. The frequency shifts in both in-plane and out-of-plane modes are dependent linearly on the oxidation content. We observe a negative trion, which is a neutral exciton bound with an electron, in the photoluminescence spectra. The binding energy of this trion is estimated to be ∼90 meV, making it a tightly bound exciton. The first-principles calculation suggests that an increase in the anion vacancy population is generally accompanied by a transition from a direct gap material to an indirect one. This opens up a new venue to engineer the electronic properties of transition metal dichalcogenides by using irradiation.

Gut microbiota, key to unlocking the door of diabetic kidney disease.

This review discusses the influence of gut microbiota dysbiosis on diabetic kidney disease through metabolite profile changes and immune and inflammatory mechanisms. We also elaborate on the mechanism of dysbiosis in the onset and development of other kidney diseases.

Biocompatible and Rapid Cyclization of Peptides with 2,4-Difluoro-6-hydroxy-1,3,5-benzenetricarbonitrile for the Development of Cyclic Peptide Libraries.

We report a biocompatible and rapid reaction between cysteine thiols and 2,4-difluoro-6-hydroxy-1,3,5-benzenetricarbonitrile (DFB), which enables the efficient cyclization of peptides in neutral aqueous solutions. The reaction was further applied to cyclize peptides displayed on the phage surface without reducing phage infectivity, thus affording high-quality cyclic peptide libraries useful for screening of cyclic peptide ligands. Using the DFB-cyclic peptide library, we identified ligands that can distinguish the pro-survival protein Bcl-xl from its close relative Bcl-2. Therefore, this study on one hand reports a useful reaction for the construction of cyclic peptide libraries, and on the other hand presents valuable hits for further design of selective Bcl-xl ligands.

Gas Sensors Based on Mechanically Exfoliated MoS2 Nanosheets for Room-Temperature NO2 Detection.

The unique properties of MoS2 nanosheets make them a promising candidate for high-performance room temperature gas detection. Herein, few-layer MoS2 nanosheets (FLMN) prepared via mechanical exfoliation are coated on a substrate with interdigital electrodes for room-temperature NO2 detection. Interestingly, compared with other NO2 gas sensors based on MoS2, FLMN gas sensors exhibit high responsivity for room-temperature NO2 detection, and NO2 is easily desorbed from the sensor surface with an ultrafast recovery behavior, with recovery times around 2 s. The high responsivity is related to the fact that the adsorbed NO2 can affect the electron states within the entire material, which is attributed to the very small thickness of the MoS2 nanosheets. First-principles calculations were carried out based on the density functional theory (DFT) to verify that the ultrafast recovery behavior arises from the weak van der Waals binding between NO2 and the MoS2 surface. Our work suggests that FLMN prepared via mechanical exfoliation have a great potential for fabricating high-performance NO2 gas sensors.

Mechanism of local electric oxidation on two-dimensional MoS2 for resistive memory application.

The manipulation and mechanism of two-dimensional (2D) transition metal dichalcogenides (TMDs) by external electric field are significant to the photoelectric properties. Herein, the 2D MoS2 nanosheets were oxidized to form MoS2-MoO3 local heterojunctions by an electric field, applied in multistable memristors for the proposal of NanoQR code. A modified thermal oxidation model was derived to reveal the mechanism of local electric oxidation on 2D MoS2. From current-voltage curves, the barrier height of the MoS2 device showed an increase of 0.39 eV due to local oxidation after applying voltage for 480 s. Based on density-functional theory, the increase of barrier height was calculated as 0.38 eV between MoS2-MoS2 and MoS2-MoO3 supercells. The 2D MoS2-MoO3 local heterojunctions were further applied as multistable memory storage at the nanoscale. The findings suggest a novel strategy for controlling local electric oxidation on 2D TMDs to manipulate the properties for the application of photoelectric memory nanodevices.

Controllable double tunneling induced transparency and solitons formation in a quantum dot molecule.

We consider the coupling effect between interdot tunneling coupling and external optical control field to study the linear optical property and the formation of temporal optical solitons in a quantum dot molecules system, analytically. The results show that the double tunneling induced transparency (TIT) windows are appeared in the absorption curve of probe field because of the formation of dynamic Stark splitting and quantum destructive interference effect from the two upper levels. Interestingly, the width of the TIT window becomes wider with the increasing intensity of the optical control field. We also find that the Kerr nonlinear effect of the probe field can be modulated effectively through coherent control both the control field and the interdot tunneling coupling in this system. Meanwhile, we demonstrate that the formation of dark or bright solitons can be practical regulated by varying the intensity of the optical control field.

Feasibility Study for the Remanufacturing of H13 Steel Heat-Treated TBM Disc Cutter Rings with Uniform Wear Failure Using GMAW.

Given that the heat treatment states of the base metal have a great influence on the surfacing repair layer, this paper carried out a feasibility study for the remanufacturing of the failed cutter rings of TBM disc cutters with uniform wear (hereinafter referred to as normally-worn ring) using the gas metal arc welding technology (GMAW). Firstly, this paper developed a heat treatment process route for H13 steel cutter rings. Secondly, the heat treatment process is numerically analyzed based on the developed route, and the rationality of the route is verified from the distribution characteristics of temperature, phase, and stress fields. Subsequently, heat treatment tests were carried out, and the physical and mechanical properties of the base metal samples prepared under laboratory conditions were evaluated respectively and systematically. Based on the comprehensive performance evaluation value calculated by the weighted comparative analysis method, it was clear that the comprehensive performance of the quenched base metal samples was 7.6% higher than that of the engineering cutter ring interior. Therefore, it is reasonable to replace the failed engineering cutter rings repaired under laboratory conditions with the prepared samples as economical alternatives. Finally, the remanufacturing of the base metal samples using GMAW was carried out, and then the remanufacturing performance of the base metal samples was analyzed. The study concluded that the comprehensive performance of the surfacing repair layer was slightly lower than that of the engineering cutter ring edge (4.1%), thus proving that the idea of surfacing remanufacturing of the normally-worn ring proposed in this paper was basically feasible.

Reactant conversion-intercalation strategy toward interlayer-expanded MoS2 microflowers with superior supercapacitor performance.

In order to avoid the complicated control and fussy procedure associated with foreign species and templates in conventional synthesis strategies, a simple reactant conversion-intercalation strategy is developed to synthesize interlayer-expanded MoS2 (E-MoS2) by employing ammonium thiocyanate converted from a thiourea reactant as intercalator. In this strategy, the thiourea plays a bifunctionality role as reactant and intercalator precursor to ensure in situ embedding into the interlayers of MoS2 to expand the interlayer spacing. The optimal E-MoS2 obtained presents superior supercapacitor performance with a specific capacity of 246.8 F g-1 at 0.5 A g-1 in 1 M Na2SO4 electrolyte in a three-electrode system, outperforming pristine MoS2 prepared by a conventional hydrothermal method (42.5 F g-1 at 0.5 A g-1). Furthermore, a symmetric supercapacitor based on an E-MoS2 electrode delivers a high specific capacity of 261.3 F g-1 and energy density of 13.3 W h kg-1 at 0.5 A g-1, and excellent cycling life with 81.7% capacity retention after 3000 cycles at 2 A g-1. Density functional theory calculations reveal that the NH4+ and SCN- can be effectively adsorbed on the surface to be inserted into the interlayers during the growth of MoS2, resulting in an expanded interlayer spacing of 9.4 Å, and the favorable electrochemical performance stems from the large Na+ adsorption capacitance and low diffusion barrier of the E-MoS2. This work offers a novel intercalation strategy that may be generally applicable to other layer-structured materials, shedding some light on the development of high-performance electrode materials via interface engineering for energy applications.