2D SnS2 crystals are attracting increasing attention owning to the huge potential for electronic and optoelectronic applications. However, batch production of 2D SnS2 crystals via a simple vapor ...process remains challenging by far. Moreover, the growth mechanism for vapor growth of 2D SnS2 is not well documented as well. Herein, a simple approach is presented for preparation of large‐scale 2D SnS2 crystals on mica sheets and it is demonstrated that these 2D crystals follow a screw‐dislocation‐driven (SDD) spiral growth process. The synthesized 2D crystals show hexagonal and truncated triangular shapes with the lateral size ranging from a few micrometers to dozens of micrometers. Observations of key features for screw dislocations, such as helical fringes, dislocation hillocks, and herringbone contours, solidly confirm the SDD spiral growth behavior of the SnS2. Possible mechanism is proposed in this work to show the generation and propagation of screw dislocations. Furthermore, in order to explore the optoelectronic property of the SnS2, photodetectors based on 2D SnS2 crystals are fabricated. The resulting device shows excellent operating characteristics, including good photo‐stability and reproducibility as well as a fast photoresponse time (≈42 ms), which enable the SnS2 a promising candidate for photodetectors.
Large scale of 2D SnS2 crystals are successfully synthesized on mica substrates. Detailed characterizations reveal that the as‐synthesized 2D crystals follow a screw‐dislocation‐driven spiral growth fashion. Photoresponse study of these 2D SnS2 crystals demonstrates their potential as a promising building block for high‐performance optoelectronic devices.
Breast cancer is the second cause of cancer mortality in women globally. Early detection, treatment, and metastasis monitoring are of great importance to favorable prognosis. Although conventional ...diagnostic methods, such as breast X-ray mammography and image positioning biopsy, are accurate, they could cause radioactive or invasive damage to patients. Liquid biopsy as a noninvasive method is convenient for repeated sampling in clinical cancer prognostic, metastatic evaluation, and relapse monitoring. MicroRNAs encased in exosomes circulating in biofluids are promising candidate cancer biomarkers because of their cancer-specific expression profiles. Here, we report an in situ detection of microRNA-1246 (miR-1246) in human plasma exosomes as breast cancer biomarker by a nucleic acid functionalized Au nanoflare probe. Needing neither time-consuming and costly isolation of exosomes from the plasma sample nor transfection means, the Au nanoflare probe can directly enter the plasma exosomes to generate fluorescent signal quantitatively by specifically targeting miR-1246. Only 40 μL of plasma is needed to incubate 4 h with the probe, giving signal sensitive enough to distinguish samples of breast cancer to normal control. Using plasma miR-1246 level detected by our assay as a marker, we differentiated 46 breast cancer patients from 28 healthy controls with 100% sensitivity and 92.9% specificity at the best cutoff. This simple, accurate, sensitive, and cost-effective liquid biopsy by the Au nanoflare probe is potent to be developed as a noninvasive breast cancer diagnostic assay for clinical adaption.
Van der Waals (vdWs) heterostructures based on 2D metals and semiconductors have attracted considerable attention due to their excellent properties and great application potential in next‐generation ...electronic and optoelectronic devices. To obtain such vdWs heterostructures, the conventional approach with artificial exfoliation and stacking of 2D metals onto 2D semiconductors in the vertical direction is still far from satisfactory, because of the low yield and impurity‐involved transfer process. Here, two‐step vapor deposition growth of 2D TaSe2‐MoSe2 metal–semiconductor heterostructures is reported. Raman maps confirm the precise spatial modulation of the as‐grown 2D TaSe2‐MoSe2 heterostructures. Structural analysis reveals that the upper 1T‐TaSe2 is formed heteroepitaxially on/around the presynthesized 2H‐MoSe2 monolayers with an epitaxial relationship of (10‐10)TaSe2//(10‐10)MoSe2 and 0001TaSe2//0001MoSe2. Based on the detailed characterizations of morphology, structure, and composition, an edge‐induced growth mechanism is proposed to illustrate the formation process of the 2D heterostructures, confirmed by first‐principle calculations. In addition, Kelvin probe force microscope characterizations and electrical transport measurements confirm that the 2D metal–semiconductor heterostructures exhibit typical rectification characteristics with a contact potential height of ≈431 mV. The direct growth of high‐quality 2D metal–semiconductor heterostructures marks an important step toward high‐performance integrated optoelectronic devices.
2D TaSe2‐MoSe2 metal–semiconductor heterostructures are successfully achieved usin an edge‐induced epitaxial growth mode. The unique contact potential and strong current rectification behavior will facilitate the development high‐performance transition metal dichalcogenide‐based electronic devices.
Improving plasticity has been an eternal theme of developing metallic materials. It is difficult to increase room‐temperature elongation of metallic materials over 100% without sacrificing strength ...using existing methods. Herein, surface‐roughness‐induced plasticity (SRIP) is discovered in biodegradable Zn–0.4Mn alloy. Surprisingly, in the good surface range that meets the international standard ISO 6892, reducing surface roughness results in significant increase in plasticity without loss of strength. From unground to 5000# sandpaper ground states, the surface roughness Ra of the alloy decreases from 0.63 to 0.05 µm, while its room temperature elongation increases from 74% to 143%. SRIP is the synergistic result of increased microstructure damage tolerance and decreased surface roughness. It provides a new method for improving plasticity.
Surface‐roughness‐induced plasticity (SRIP) solves the dilemma of significantly improving plasticity at the expense of strength. From the unground state to the 5000# sandpaper ground state, room‐temperature elongation of biodegradable Zn–0.4Mn alloy increases from 74% to 143% without loss of strength. SRIP is the synergistic result of increased microstructure damage tolerance and decreased surface roughness.
•The initial level of cyberbullying (perpetration and victimization) significantly predicted the initial level of loneliness.•The change rate of cyberbullying (perpetration and victimization) ...positively predicted the change rate of loneliness.•The initial level of cyberbullying victimization was negatively correlated with the growth rate of cyberbullying victimization.•General trust played a bidirectional mediating role between cyberbullying (perpetration and victimization) and loneliness.
Atomically thin hexagonal boron nitride (h‐BN) is gaining significant attention for many applications such as a dielectric layer or substrate for graphene‐based devices. For these applications, ...synthesis of high‐quality and large‐area h‐BN layers with few defects is strongly desirable. In this work, the aligned growth of millimeter‐size single‐crystal h‐BN domains on epitaxial Ni (111)/sapphire substrates by ion beam sputtering deposition is demonstrated. Under the optimized growth conditions, single‐crystal h‐BN domains up to 0.6 mm in edge length are obtained, the largest reported to date. The formation of large‐size h‐BN domains results mainly from the reduced Ni‐grain boundaries and the improved crystallinity of Ni film. Furthermore, the h‐BN domains show well‐aligned orientation and excellent dielectric properties. In addition, the sapphire substrates can be repeatedly used with almost no limit. This work provides an effective approach for synthesizing large‐scale high‐quality h‐BN layers for electronic applications.
The aligned growth of 0.6 mm single‐crystal hexagonal boron nitride (h‐BN) domains is realized on epitaxial Ni(111)/sapphire by ion beam sputtering deposition. The formation of large‐size h‐BN domains results mainly from the reduced Ni‐grain boundaries and the improved crystallinity of the Ni film. In addition, the h‐BN domains show well‐aligned orientation and excellent dielectric properties.
Lysine‐specific demethylase 5A (KDM5A) has recently become a promising target for epigenetic therapy. In this study, we designed and synthesized metal complexes bearing ligands with reported ...demethylase and p27 modulating activities. The Rh(III) complex 1 was identified as a direct, selective and potent inhibitor of KDM5A that directly abrogate KDM5A demethylase activity via antagonizing the KDM5A‐tri‐/di‐methylated histone 3 protein–protein interaction (PPI) in vitro and in cellulo. Complex 1 induced accumulation of H3K4me3 and H3K4me2 levels in cells, causing growth arrest at G1 phase in the triple‐negative breast cancer (TNBC) cell lines, MDA‐MB‐231 and 4T1. Finally, 1 exhibited potent anti‐tumor activity against TNBC xenografts in an in vivo mouse model, presumably via targeting of KDM5A and hence upregulating p27. Moreover, complex 1 was less toxic compared with two clinical drugs, cisplatin and doxorubicin. To our knowledge, complex 1 is the first metal‐based KDM5A inhibitor reported in the literature. We anticipate that complex 1 may be used as a novel scaffold for the further development of more potent epigenetic agents against cancers, including TNBC.
A rhodium(III)‐based complex has been discovered as an inhibitor of KDM5A, an epigenetic target for triple‐negative breast cancer. The complex inhibited the KDM5A–H3K4me3 interaction and suppressed proliferation of triple‐negative breast cancer (TNBC) tumors in mice and may be used as a novel scaffold for further development of more potent epigenetic agents against cancers, including TNBC.
In this work, we propose a new configuration of surface plasmon resonance (SPR) sensor that is based on graphene–MoS2 hybrid structures for ultrasensitive detection of molecules. The proposed system ...displays a phase-sensitivity enhancement factor of more than 500-fold when compared to the SPR sensing scheme without the graphene–MoS2 coating or with only graphene coating. Our hypothesis is that the monolayer MoS2 has a much higher optical absorption efficiency (∼5%) than that of the graphene layer (∼2.3%). Based on our findings, the electron energy loss of MoS2 layer is comparable to that of graphene and this will allow a successful (∼100%) of light energy transfer to the graphene–MoS2 coated sensing substrate. Such process will lead to a significant enhancement of SPR signals. Our simulation shows that a quasi-dark point of the reflected light can be achieved under this condition and this has resulted in a steep phase jump at the resonance angle of our newly proposed SPR system. More importantly, we found that phase interrogation detection approach of the graphene–MoS2 hybrid structures-based sensing system is more sensitive than that of using the regularly angular interrogation method and our theoretical analysis indicates that 45nm of Au film thickness and 3 coating layers of MoS2 nanosheet are the optimized parameters needed for the proposed SPR system to achieve the highest detection sensitivity range.
Skeletal reorganization reactions have emerged as an intriguing tool for converting readily available compounds into complicated molecules inaccessible by traditional methods. Herein, we report a ...unique skeleton‐reorganizing coupling reaction of cycloheptatriene and cycloalkenones with amines. In the presence of Rh/acid catalysis, cycloheptatriene can selectively couple with anilines to deliver fused 1,2‐dihydroquinoline products. Mechanistic studies indicate that the retro‐Mannich type ring‐opening and subsequent intramolecular Povarov reaction account for the ring reorganization. Our mechanistic studies also revealed that skeleton‐reorganizing amination between anilines and cycloalkenones can be achieved with acid. The synthetic utilization of this skeleton‐reorganizing coupling reaction was showcased with a gram‐scale reaction, synthetic derivatizations, and the late‐stage modification of commercial drugs.
An unusual catalytic coupling reaction of cycloheptatriene and cycloalkenones with amines proceeds through a skeleton‐reorganization process for the selective synthesis of fused 1,2‐dihydroquinolines. Mechanistic studies indicate that the reactions proceed through a retro‐Mannich‐type ring‐opening and a subsequent intramolecular Povarov process.
Undecorated and Pt-decorated SnO2 nanoparticles (NPs) were prepared using sol-gel and hydrothermal methods. The tin dioxide NPs, as sensing materials, were screen printed on alumina substrates with ...Pt test electrode to fabricate the gas sensors. The characteristics of these gas sensors in terms of composition, morphology, and sensing property were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and electrochemical workstation, respectively. The results elucidated that the response time of Pt-decorated SnO2 sensor to 100 ppm H2 is 29 s at 350 °C, which is almost half of that of pure SnO2 gas sensor. Meanwhile, the effect of operating temperature and Pt decorating on the sensing properties and the ‘n’ value is studied. Comparing with many fabricated H2 gas sensors, our as-prepared sensor exhibits not only a high response time but also detects H2 gas down to 0.08 ppm. To the author's best knowledge, the detection limit of 0.08 ppm is the best reported detection limit for the gas sensors based on tin oxide NPs so far. Moreover, there is a significant enhancement in the selectivity of Pt-decorated SnO2 sensor to the H2 gas against other investigated gases such as carbon monoxide (CO), methane (CH4), nitrogen dioxide (NO2), sulfur dioxide (SO2). Overall, the obtained results clearly demonstrate that the Pt-decorated SnO2 is an excellent sensing material for the fabrication of gas sensors and the detection of trace concentration of H2 down to 0.08 ppm. Furthermore, the results of statistical and fractal analysis on 2D microstructures of FESEM images showed a coefficient correlation of about 0.991 for all the samples.
•Pt-SnO2 was synthesized using sol-gel and hydrothermal techniques.•The influence of ‘n’ value on the sensing properties of the fabricated gas sensors is discussed in details.•Pt-SnO2 gas sensors demonstrated excellent sensing properties and can detect H2 down to 0.08 ppm.
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