Carbon dots (CDs) are photoluminescent nanomaterials with wide-ranging applications. Despite their photoactivity, it remains unknown whether CDs degrade under illumination and whether such ...photodegradation poses any cytotoxic effects. Here, we show laboratory-synthesized CDs irradiated with light degrade into molecules that are toxic to both normal (HEK-293) and cancerous (HeLa and HepG2) human cells. Eight days of irradiation photolyzes 28.6-59.8% of the CDs to <3 kilo Dalton molecules, 1431 of which are detected by high-throughput, non-target high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Molecular network and community analysis further reveal 499 cytotoxicity-related molecules, 212 of which contain polyethylene glycol, glucose, or benzene-related structures. Photo-induced production of hydroxyl and alkyl radicals play important roles in CD degradation as affected by temperature, pH, light intensity and wavelength. Commercial CDs show similar photodegraded products and cytotoxicity profiles, demonstrating that photodegradation-induced cytotoxicity is likely common to CDs regardless of their chemical composition. Our results highlight the importance of light in cytocompatibility studies of CDs.
This paper analyses the dynamic dependence between WTI crude oil and the exchange rates of the United States and China, taking structural changes of dependence into account by using six time-varying ...copula models. Upside and downside conditional values at risk (CoVaRs) are introduced specifically to measure the upward and downward risk dependences between oil prices and exchange rates. The findings indicate a structural break point of dependence exists between daily or weekly crude oil and the US dollar index. The dependence between crude oil and the RMB exchange rate is faintly positive with lower tail dependence, while the dependence between crude oil and the US dollar index is significantly negative with lower-upper and upper-lower tail dependence. Finally, the CoVaRs results show that there is significant risk spillover from crude oil to Chinese and the US exchange rate markets. Furthermore, the spillover effect is significantly asymmetry in Chinese exchange rate market in response to rising and falling oil returns, while the asymmetry of spillover effect for the US dollar index is not significant.
•Dynamic dependences between oil returns and exchange rates are analysed.•Risk spillover measured by CoVaR is estimated by six time-varying copula models.•A structural change of dependence for USD-WTI has been detected.•The dependence of CNY-WTI is weakly positive, while that of USD-WTI is negative.•There is significant risk spillover from WTI to exchange rates of China and the US.
Exploring 2D ultrawide bandgap semiconductors (UWBSs) will be conductive to the development of next‐generation nanodevices, such as deep‐ultraviolet photodetectors, single‐photon emitters, and ...high‐power flexible electronic devices. However, a gap still remains between the theoretical prediction of novel 2D UWBSs and the experimental realization of the corresponding materials. The cross‐substitution process is an effective way to construct novel semiconductors with the favorable parent characteristics (e.g., structure) and the better physicochemical properties (e.g., bandgap). Herein, a simple case is offered for rational design and syntheses of 2D UWBS GaPS4 by employing state‐of‐the‐art GeS2 as a similar structural model. Benefiting from the cosubstitution of Ge with lighter Ga and P, the GaPS4 crystals exhibit sharply enlarged optical bandgaps (few‐layer: 3.94 eV and monolayer: 4.50 eV) and superior detection performances with high responsivity (4.89 A W−1), high detectivity (1.98 × 1012 Jones), and high quantum efficiency (2.39 × 103%) in the solar‐blind ultraviolet region. Moreover, the GaPS4‐based photodetector exhibits polarization‐sensitive photoresponse with a linear dichroic ratio of 1.85 at 254 nm, benefitting from its in‐plane structural anisotropy. These results provide a pathway for the discovery and fabrication of 2D UWBS anisotropic materials, which become promising candidates for future solar‐blind ultraviolet and polarization‐sensitive sensors.
A cross‐substitution process is used to design 2D ultrawide‐bandgap semiconductor GaPS4 by employing GeS2 as a similar structural model. Monolayer GaPS4 exhibits an ultrawide optical bandgap of 4.50 eV. The polarization‐sensitive photodetectors based on the GaPS4 material display high selectivity and linear dichroic ratio in the solar‐blind ultraviolet region.
The conductive hydrogels always suffered from high internal friction, large hysteresis, and low capability of accurately predicting physical deformation, which seriously restricted their application ...in smart wearable devices. To address these problems, solvent molecules are directionally inserted into the polymer molecule chains via bridge effect to effectively reduce the molecular internal friction. Moreover, swelling is also combined to eliminate the temporary entanglements in the hydrogel system. The cooperation between the bridge and swollen effect endows the prepared polyacrylamide (PAM)/laponite/H3BO3/ethylene glycol (Eg) organohydrogel (PLBOH) ultralow hysteresis (1.38%, ε = 100%), ultrafast response (≈10 ms), and high linearity in the whole‐strain‐range (R2 = 0.996) with a great sensitivity (GF = 2.68 at the strain range of 0–750%). Meanwhile, the prepared PL10B30OH exhibits long‐term stability, excellent stretchability, and low dissipated energy. Furthermore, the assembled triboelectric nanogenerator (TENG) displays an outstanding energy harvesting performance with an output voltage of 200 V with the size of 20 mm × 20 mm. The assembled strain sensors can monitor the small strain of facial expressions and large strain of human movements, indicating the tremendous applications in self‐powered intelligent and flexible wearable electronics under harsh environmental conditions.
An innovative method is developed to prepare the hydrogel via bridge effect to directionally insert solvent molecules into the hydrogel, which effectively acts as lubricate to reduce the molecular internal friction. The developed hydrogel exhibits ultralow‐hysteresis, ultrafast‐response, and whole‐strain‐range linearity contributed by the special molecular structure, which also holds great potential in flexible wearable devices.
As artificial intelligent technologies have been increasingly applied in tourism and hospitality industry, the service failure caused by artificial intelligence assistant and how to recover them are ...worth empirical studying. Laboratory experiments were employed to test the impact of cuteness in service failure, with effective manipulation of cute appearance, cute voice and cute language style of artificial intelligence assistant. By utilizing three studies with seven experiments, this research demonstrated the positive effect of cuteness design of artificial intelligence assistant on customer tolerance of service failure and further revealed the two mediating paths (tenderness and performance expectancy) as well as the boundary (failure severity and time pressure) of the cuteness effect. These findings contribute to the knowledge on artificial intelligent assistant service and provide insight for cute design using in tourism and hospitality industry.
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•Cuteness design of AI assistant influences customers' tolerance of service failure.•Seven experiments were used to examine the cuteness effect and the mechanism behind.•Cuteness can be designed through appearance, voice or language style.•Cuteness effect was mediated by tenderness and performance expectancy.•The moderating role of perceived severity and time pressure was found.
Birefringence and dichroism are very important properties in optical anisotropy. Understanding the intrinsic birefringence and dichroism of a material can provide great help to utilize its optical ...anisotropy. But the direct experimental investigation of birefringence in nanoscale materials is rarely reported. As typical anisotropic transition metals trichalcogenides (TMTCs) materials with quasi‐1D structure, TiS3 and ZrS3 have attracted extensive attention due to their special crystal structure and optical anisotropy characteristics. Here, the optical anisotropy properties such as birefringence and dichroism of two kinds of quasi‐1D TMTCs, TiS3 and ZrS3, are theoretically and experimentally studied. In experimental results, the anisotropic refraction and anisotropic reflection of TiS3 and ZrS3 are studied by polarization‐resolved optical microscopy and azimuth‐dependent reflectance difference microscopy, respectively. In addition, the birefringence and dichroism of ZrS3 nanoribbon in experiment are directly measured by spectrometric ellipsometry measurements, and a reasonable result is obtained. This work provides the basic optical anisotropy information of TiS3 and ZrS3. It lays a foundation for the further study of the optical anisotropy of these two materials and provides a feasible method for the study of birefringence and dichroism of other nanomaterials in the future.
Optical anisotropy of quasi‐1D transition metals trichalcogenides of TiS3 and ZrS3 including anisotropic refraction, anisotropic reflection, birefringence, and dichroism are systematically investigated in experimental setup. Anisotropic refraction of TiS3 and ZrS3 nanoribbons are expressed by polarization‐resolved optical microscopy, and anisotropic reflection are expressed by azimuth‐dependent reflectance difference microscopy. Birefringence and dichroism of ZrS3 are measured by Mueller matrix spectrometric ellipsometry.
It is revealed that Xiaoyaosan could reduce glutamate level in the hippocampus of depressed rats, whose metabolism leads to the pathophysiology of depression. However, the underlying mechanism ...remains unclear. This study aims to explore the effect of Xiaoyaosan on glutamate metabolism, and how to regulate the excitatory injury caused by glutamate.
Rats were induced by chronic unpredictable mild stress, then divided into control, vehicle (distilled water), Xiaoyaosan, fluoxetine, vehicle (DMSO), Xiaoyaosan + Ly294002 and Ly294002 groups. Ly294002 was microinjected into the lateral ventricular catheterization at 5 mM. Xiaoyaosan (2.224 g/kg) and fluoxetine (2.0 mg/kg) were orally administered for three weeks. The open field test (OFT), forced swimming test (FST), and sucrose preference test (SPT) were used to assess depressive behavior. The glutamate and corticosterone (CORT) levels were detected by ELISA. Western blot, immunochemistry or immunofluorescence were used to detect the expressions of NR2B, MAP2, PI3K and P-AKT/Akt in the hippocampal CA1 region. The mRNA level of MAP2, NR2B and PI3K were detected by RT-qPCR.
Compared to the rats in control group, body weight and food intake of CUMS rats was decreased. CUMS rats also showed depression-like behavior as well as down regulate the NR2B and PI3K/Akt signaling pathway. Xiaoyaosan treatments could increase food intake and body weight as well as improved time spent in the central area, total distance traveled in the OFT. Xiaoyaosan could also decrease the immobility time as well as increase the sucrose preference in SPT. Moreover, xiaoyaosan decreased the level of glutamate in the hippocampal CA1 region and serum CORT in CUMS rats. Furthermore, xiaoyaosan improved the expression of MAP2 as well as increased the expression of NR2B, PI3K and the P-AKT/AKT ratio in the hippocampal CA1 region in the CUMS rats.
Xiaoyaosan treatment can exert the antidepressant effect by rescuing hippocampal neurons loss induced by the glutamate-mediated excitotoxicity in CUMS rats. The underlying pathway maybe through NR2B and PI3K/Akt signaling pathways. These results may suggest the potential of Xiaoyaosan in preventing the development of depression.
Investigating carbon congestion effect can help identify congestion in production, which is of great significance for the rational use of resources and the effective promotion of carbon emissions ...reduction. Under this circumstance, this study uses the dual model of radial DEA to explore both undesirable/desirable congestion, returns to damage and damages to return during 2005–2015 from both provincial and sectoral levels. Combined with window analysis, the technical efficiency and emissions reduction potential of China's industrial sectors are also discussed. The empirical results show that: (1) China's industrial carbon congestion is obvious and the congestion effect witnesses a trend of regional agglomeration and evident regional and sectoral heterogeneity. In particular, undesirable congestion mainly occurs in the eastern region, and desirable congestion mainly occurs in the western region, followed by the eastern region; both undesirable and desirable congestions mainly occur in some sectors in the Manufacturing and Power-Gas-Water industries. (2) If all sectors produce on the production frontier, the average annual potential carbon emissions reduction would reach 722.82 million tons, with the higher potential in western region and Shanxi province of central region, as well as Manufacturing and six high-energy-consuming sectors. (3) To achieve the “win-win” of industrial development and carbon emissions reduction, China's western region should focus on green technology innovation, while the eastern region and Power-Gas-Water industry should focus on both input resources optimisation and green technology innovation.
•It explores both undesirable and desirable congestion of China's industrial sectors.•It uses the dual model of radial DEA to quantify the state of carbon congestion.•The congestion effect witnesses evident regional and sectoral heterogeneity.•East and central regions and PGW industry should optimise input resources.•Northeast and west regions and PGW industry should innovate ecological technology.
The interfacial tunable band alignment of heterostructures is coveted in device design and optimization of device performance. As an intentional approach, alloying allows band engineering and ...continuous band‐edge tunability for low‐dimensional semiconductors. Thus, combining the tunability of alloying with the band structure of a heterostructure is highly desirable for the improvement of device characteristics. In this work, the single‐step growth of alloy‐to‐alloy (MoS2(1‐x)Se2x/SnS2(1‐y)Se2y) 2D vertical heterostructures is demonstrated. Electron diffraction reveals the well‐aligned heteroepitaxial relationship for the heterostructure, and a near‐atomically sharp and defect‐free boundary along the interface is observed. The nearly intrinsic van der Waals (vdW) interface enables measurement of the intrinsic behaviors of the heterostructures. The optimized type‐II band alignment for the MoS2(1‐x)Se2x/SnS2(1‐y)Se2y heterostructure, along with the large band offset and effective charge transfer, is confirmed through quenched PL spectroscopy combined with density functional theory calculations. Devices based on completely stacked heterostructures show one or two orders enhanced electron mobility and rectification ratio than those of the constituent materials. The realization of device‐quality alloy‐to‐alloy heterostructures provides a new material platform for precisely tuning band alignment and optimizing device applications.
The single‐step growth of alloy/alloy (MoS2(1‐x)Se2x/SnS2(1‐y)Se2y) vertical heterostructures is demonstrated and the heterostructure exhibits a nearly intrinsic van der Waals (vdW) interface in terms of a near‐atomically sharp and defect‐free boundary along the interface as well as a well‐aligned epitaxial relationship. The almost‐ideal interface enables the identification of the intrinsic behavior of the heterostructures such as the band alignment, charge transfer, and carrier transport.
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