X-ray detection, which plays an important role in medical and industrial fields, usually relies on inorganic scintillators to convert X-rays to visible photons; although several high-quantum-yield ...fluorescent molecules have been tested as scintillators, they are generally less efficient. High-energy radiation can ionize molecules and create secondary electrons and ions. As a result, a high fraction of triplet states is generated, which act as scintillation loss channels. Here we found that X-ray-induced triplet excitons can be exploited for emission through very rapid, thermally activated up-conversion. We report scintillators based on three thermally activated delayed fluorescence molecules with different emission bands, which showed significantly higher efficiency than conventional anthracene-based scintillators. X-ray imaging with 16.6 line pairs mm
resolution was also demonstrated. These results highlight the importance of efficient and prompt harvesting of triplet excitons for efficient X-ray scintillation and radiation detection.
Abstract
There is great interest in the development of micromotors which can convert energy to motion in sub-millimeter dimensions. Micromachines take the micromotor concept a step further, ...comprising complex systems in which multiple components work in concert to effectively realize complex mechanical tasks. Here we introduce light-driven micromotors and micromachines that rely on optoelectronic tweezers (OET). Using a circular micro-gear as a unit component, we demonstrate a range of new functionalities, including a touchless micro-feed-roller that allows the programming of precise three-dimensional particle trajectories, multi-component micro-gear trains that serve as torque- or velocity-amplifiers, and micro-rack-and-pinion systems that serve as microfluidic valves. These sophisticated systems suggest great potential for complex micromachines in the future, for application in microrobotics, micromanipulation, microfluidics, and beyond.
Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death and it has been confirmed that increased low density lipoprotein cholesterol (LDL-C) is an independent risk factor for ...atherosclerosis. Recently, the increasing evidence has showed that hypertriglyceridemia is associated with incremental ASCVD risk. But the proatherogenic mechanism of triglyceride (TG) remains unclear. Therefore, this article focuses on the clinical studies and proatherogenic mechanism related to hypertriglyceridemia, in order to provide reference for the prevention and treatment of ASCVD.
MicroRNAs are endogenous single-stranded non-coding small RNA molecules that can be secreted into the circulation and exist stably. They usually exhibit aberrant expression under different ...physiological and pathological conditions. Recently, differentially expressed circulating microRNAs were focused on as potential biomarkers for cancer screening. We herein review the role of circulating microRNAs for cancer diagnosis, tumor subtype classification, chemo- or radio-resistance monitoring, and outcome prognosis. Moreover, circulating microRNAs still have several issues hindering their reliability for the practical clinical application. Future studies need to elucidate further potential application of circulating microRNAs as specific and sensitive markers for clinical diagnosis or prognosis in cancers.
Abstract
Zero-dimensional MoS
2
quantum dots (QDs) possess distinct physical and chemical properties, which have garnered them considerable attention and facilitates their use in a broad range of ...applications. In this study, we prepared monolayer MoS
2
QDs using temporally shaped femtosecond laser ablation of bulk MoS
2
targets in water. The morphology, crystal structures, chemical, and optical properties of the MoS
2
QDs were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectra, and photoluminescence spectra. The analysis results show that highly pure, uniform, and monolayer MoS
2
QDs can be successfully prepared. Moreover, by temporally shaping a conventional single pulse into a two-subpulse train, the production rate of MoS
2
nanomaterials (including nanosheets, nanoparticles, and QDs) and the ratio of small size MoS
2
QDs can be substantially improved. The underlying mechanism is a combination of multilevel photoexfoliation of monolayer MoS
2
and water photoionization–enhanced light absorption. The as-prepared MoS
2
QDs exhibit excellent electrocatalytic activity for hydrogen evolution reactions because of the abundant active edge sites, high specific surface area, and excellent electrical conductivity. Thus, this study provides a simple and green alternative strategy for the preparation of monolayer QDs of transition metal dichalcogenides or other layered materials.
Amorphous molybdenum sulfide (a‐MoSx) is regarded as a promising electrocatalyst for hydrogen evolution reaction (HER) due to its disorder structures with a significant number of defect‐rich active ...sites. Here, a green, one‐step, and controllable method is developed to photoregulate the chemical reactions and synthesize nanosized a‐MoSx by temporally shaped femtosecond laser ablation of ammonium tetrathiomolybdate aqueous solution. By adjusting the laser energy and pulse delay to control photoinduced and/or photothermal‐induced reduction/oxidation, the S to Mo ratio x can be modulated from 1.53 to 3.07 and the ratio of the MoV defect species, bridging S22−, and terminal S22− ligands can be controlled. The optimized a‐MoSx catalysts (x = 2.73) exhibit high catalytic activity with a low Tafel slope of 40 mV dec−1, high double‐layer capacitance of 74.47 mF cm−2, and large current density of 516 mA cm−2 at an overpotential of 250 mV. The high catalytic activity can be mainly attributed to MoV defect species and bridging S22− ligands, or most likely dominated by the MoV defect species. This study not only provides an alternatively controllable method to prepare a‐MoSx as efficient HER catalysts but also contributes to the understanding of the origin of its catalytic activity.
For the first time, various material compositions of nanosized amorphous MoSx (from amorphous MoS2 to amorphous MoS3) are successfully synthesized through photomodulation of the reaction mechanisms (from photothermal‐induced to photoinduced reduction/oxidation). The catalysts with optimized ratios of active sites of MoV defect species, bridging S22− ligands, and terminal S22− ligands exhibit excellent catalytic activity.
Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy may pose adverse health risk to both the mothers and babies. In the present study, 188 pregnant women of different trimesters were ...recruited in Guangzhou, south China, and nine hydroxyl PAHs (OH-PAHs) and a biomarker of DNA oxidative damage, 8-hydroxy-2′-deoxyguanosine (8-OHdG), were determined in their urine samples. All OH-PAHs except for 4-hydroxyphenanthrene and 6-hydroxychrysene were found in > 90% samples, with total concentration in the range of 0.52 to 42.9 μg/g creatinine. In general, concentration levels of OH-PAHs in pregnant women were lower than those in general population in the same research area but with higher levels in working women than in housewives. The mean daily intakes of PAHs from dietary estimated by urinary OH-PAHs were 0.021, 0.004, 0.047, and 0.030 μg/kg_bw/day for naphthalene, fluorene, phenanthrene, and pyrene, respectively, which were much lower than the reference doses (20, 30, and 40 μg/kg_bw/day for naphthalene, pyrene, and fluorene, respectively) derived from chronic oral exposure data by the United States Environmental Protection Agency. The low exposure levels of PAHs may be attributed to the traditional dietary taboo of Chinese pregnant women, which is to minimize the consumption of “toxic” food. The concentrations of 8-OHdG (4.67–49.4 μg/g creatinine) were significantly positively correlated with concentrations of several OH-PAHs, such as metabolites of naphthalene, fluorene, and phenanthrene (
r
= 0.3–0.6). In addition, the concentrations of 8-OHdG were higher in working women than in housewives when exposed to the same levels of PAHs, partly indicating the possible relation between work-related pressure for working women and the oxidative stress.
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•FeS2@SiO2 microspheres were firstly employed to activate persulfate (PS).•UV induced a significant improvement in the degradation of bisphenol A (BPA).•A synergistic effect between ...photochemical and catalytic processes was achieved.•SO4− radicals prevailed over HO in the FeS2@SiO2 microspheres/PS/UV system.•A possible reaction pathway and mechanism of BPA degradation was proposed.
In this study, FeS2@SiO2 microspheres were firstly employed as a heterogeneous catalyst to activate persulfate (PS) for the degradation of bisphenol A (BPA) from aqueous solutions. The most relevant findings revealed that UV irradiation induced a significant improvement in the degradation of BPA by the FeS2@SiO2 microspheres/PS system. Nearly 100% of BPA degradation by the FeS2@SiO2 microspheres/PS/UV system was achieved within 120 min at reaction conditions of 1 mM PS, 0.066 mM BPA, 1.0 g/L FeS2@SiO2 microspheres and pH 3.0. A high performance on the degradation of BPA might be attributable to a synergistic effect between the PS/UV and the FeS2@SiO2 microspheres/PS catalytic processes. It was found that the BPA degradation could be inhibited by the coexisting anions like Cl−, HCO3− and PO43− to different extents at much higher concentrations, whereas NO3− had a negligible effect. Organic acids such as ethylene diamine tetra-acetic acid (EDTA) and oxalic acid (OA) would lead to an enhancement with a lower dosage, whereas a significantly negative effect was observed at much higher dosages. Radical scavenging tests revealed that the SO4− radicals prevailed over HO. A total of seven intermediates during the degradation of BPA were identified by GC/MS, and a possible reaction pathway and mechanism of BPA degradation by the FeS2@SiO2 microspheres/PS/UV system was proposed. This study demonstrated a simple water treatment method involving the use of low cost natural iron minerals for organic pollutants removal.
The pollution of heavy metals and organic compounds has received increased attention in recent years. In the current study, a novel biochar-based iron oxide composite (FeYBC) was successfully ...synthesized using pomelo peel and ferric chloride solution through one-step process at moderate temperature. Results clearly demonstrate that FeYBC exhibited more efficient removal of Cr(VI) and/or phenol compared with the pristine biochar, and the maximum adsorption amounts of Cr(VI) and phenol by FeYBC could reach 24.37 and 39.32 mg g−1, respectively. A series of characterization data suggests that several iron oxides such as Fe2O3, Fe0, FeOOH and Fe3O4 were formed on the FeYBC surface as well as oxygen-containing groups. Thermodynamics study indicates that Cr(VI) and phenol adsorption by FeYBC were endothermic and exothermic processes, respectively. Langmuir adsorption isotherm and pseudo-second order models could better explain the Cr(VI) and phenol adsorption behaviors over FeYBC. The Cr(VI) adsorption might be primarily achieved through the ion exchange and surface complexation and reduction, whereas the π–π interaction and electron donor–acceptor complex mainly contributed to phenol adsorption. The findings indicate that the biochar-based iron oxide composites material was an efficient adsorbent for the remediation of industrial effluents containing Cr(VI) and phenol.
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•A novel biochar-based iron oxide composite (FeYBC) was firstly synthesized.•FeYBC exhibited more efficient Cr(VI) and phenol removal than pristine biochar.•Langmuir and pseudo second order models well explain Cr(VI) and phenol adsorption.•Cr(VI) and phenol adsorption were endothermic and exothermic nature, respectively.•The possible removal mechanism of both Cr(VI) and phenol adsorption was proposed.
Although perovskite X-ray detectors have revealed promising properties, their dark currents are usually hundreds of times larger than the practical requirements. Here, we report a detector ...architecture with a unique shunting electrode working as a blanking unit to suppress dark current, and it theoretically can be reduced to zero. We experimentally fabricate the dark-current-shunting X-ray detector, which exhibits a record-low dark current of 51.1 fA at 5 V mm
, a detection limit of 7.84 nGy
s
, and a sensitivity of 1.3 × 10
μC Gy
cm
. The signal-to-noise ratio of our polycrystalline perovskite-based detector is even outperforming many previously reported state-of-the-art single crystal-based X-ray detectors by serval orders of magnitude. Finally, the proof-of-concept X-ray imaging of a 64 × 64 pixels dark-current-shunting detector array is successfully demonstrated. This work provides a device strategy to fundamentally reduce dark current and enhance the signal-to-noise ratio of X-ray detectors and photodetectors in general.
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