It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g‐C3N4) could participate in ammonia (NH3) synthesis during the photocatalytic ...nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g‐C3N4 nanosheets can indeed be hydrogenated and contribute to NH3 synthesis during the visible‐light photocatalytic NRR. However, these exposed N atoms can be firmly stabilized through forming BNC coordination by means of B‐doping in g‐C3N4 nanosheets (BCN) with a B‐doping content of 13.8 wt%. Moreover, the formed BNC coordination in g‐C3N4 not only effectively enhances the visible‐light harvesting and suppresses the recombination of photogenerated carriers in g‐C3N4, but also acts as the catalytic active site for N2 adsorption, activation, and hydrogenation. Consequently, the as‐synthesized BCN exhibits high visible‐light‐driven photocatalytic NRR activity, affording an NH3 yield rate of 313.9 µmol g−1 h−1, nearly 10 times of that for pristine g‐C3N4. This work would be helpful for designing and developing high‐efficiency metal‐free NRR catalysts for visible‐light‐driven photocatalytic NH3 synthesis.
The BNC coordination formed by boron doping in g‐C3N4 nanosheets is the catalytic active site for the high‐efficiency photocatalytic nitrogen reduction reaction. It also effectively immobilizes the exposed active N atoms of g‐C3N4, inhibits the recombination of photogenerated charges, and improves the visible‐light harvesting efficiency.
Abstract
The organic-inorganic hybrid lead halide perovskites have emerged as a series of star materials for solar cells, lasers and detectors. However, the issues raised by the toxic lead element ...and marginal stability due to the volatile organic components have severely limited their potential applications. In this work, we develop a nucleation-controlled solution method to grow large size high-quality Cs
3
Bi
2
I
9
perovskite single crystals (PSCs). Using the technique, we harvest some centimeter-sized single crystals and achieved high device performance. We find that X-ray detectors based on PSCs exhibit high sensitivity of 1652.3 μC Gy
air
−1
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and very low detectable dose rate of 130 nGy
air
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, both desired in medical diagnostics. In addition, its outstanding thermal stability inspires us to develop a high temperature X-ray detector with stable response at up to 100 °C. Furthermore, PSCs exhibit high X-ray imaging capability thanks to its negligible signal drifting and extremely high stability.
Co/CoO nanoparticles immobilized on Co-N-doped carbon were successfully developed using shrimp-shell derived N-doped carbon nanodots as precursors by a combined approach of polymerization and ...pyrolysis, as electrocatalysts exhibiting trifunctional catalytic activities toward oxygen reduction, oxygen evolution and hydrogen evolution reactions and high performance in rechargeable zinc-air batteries.
Abstract
Background
Prostate cancer (PC) is common male cancer with high mortality worldwide. Emerging evidence demonstrated that long noncoding RNAs (lncRNAs) play critical roles in various type of ...cancers including PC by serving as competing endogenous RNAs (ceRNAs) to modulate microRNAs (miRNAs). LncRNA activated by DNA damage (NORAD) was found to be upregulated in PC cells, while the detailed function and regulatory mechanism of NORAD in PC progression remains largely unclear.
Methods
Expression of NORAD in PC tissues and cell lines were detected by real-time quantitative PCR (qRT-PCR). NORAD was respectively overexpressed and knocked down by transfection with pcDNA-NORAD and NORAD siRNA into PC-3 and LNCap cells. Cell proliferation, invasion and apoptosis were determined by using CCK-8, Transwell and Flow cytometry assays, respectively. The target correlations between miR-30-5p and NORAD or RAB11A were confirmed by using dual luciferase reporter assay. Moreover, expression levels of RAB11A, the epithelial-mesenchymal transition (EMT) marker proteins and the Wnt pathway related proteins were measured by Western blotting. Tumor xenograft assay was used to study the effect of NORAD on tumor growth in vivo.
Results
NORAD was upregulated in PC tissues and cells. Overexpression of NORAD promoted cell proliferation, invasion, EMT, and inhibited cell apoptosis; while knockdown of NORAD had the opposite effect. NORAD was found to be functioned as a ceRNA to bind and downregulated miR-30a-5p that was downregulated in PC tumor tissues. Rescue experiments revealed that miR-30a-5p could weaken the NORAD-mediated promoting effects on cell proliferation, invasion and EMT. Furthermore, RAB11A that belongs to a member of RAS oncogene family was verified as a target of miR-30a-5p, and reintroduction of RAB11A attenuated the effects of miR-30a-5p overexpression on cell proliferation, invasion, EMT and apoptosis of PC cells. More importantly, silencing RAB11A partially reversed the promoting effects of NORAD overexpression on cell proliferation, invasion and EMT of PC cells via the WNT/β-catenin pathway. Lastly, tumorigenicity assay in vivo demonstrated that NORAD increased tumor volume and weight via miR-30a-5p /RAB11A pathway.
Conclusion
Our results indicated a significant role of NORAD in mechanisms associated with PC progression. NORAD promoted cell proliferation, invasion and EMT via the miR-30a-5p/RAB11A/WNT/β-catenin pathway, thus inducing PC tumor growth.
Thinness‐controlled perovskite wafers are directly prepared using a geometry‐regulated dynamic‐flow reaction system. It is found that the wafers are a superior material for photodetectors with a ...photocurrent response ≈350 times higher than that made of microcrystalline thin films. Moreover, the wafers are compatible with mass production of integrated circuits.
By fine‐tuning the crystal nucleation and growth process, a low‐temperature‐gradient crystallization method is developed to fabricate high‐quality perovskite CH3NH3PbBr3 single crystals with high ...carrier mobility of 81 ± 5 cm2 V−1 s−1 (>3 times larger than their thin film counterpart), long carrier lifetime of 899 ± 127 ns (>5 times larger than their thin film counterpart), and ultralow trap state density of 6.2 ± 2.7 × 109 cm−3 (even four orders of magnitude lower than that of single‐crystalline silicon wafers). In fact, they are better than perovskite single crystals reported in prior work: their application in photosensors gives superior detectivity as high as 6 × 1013 Jones, ≈10–100 times better than commercial sensors made of silicon and InGaAs. Meanwhile, the response speed is as fast as 40 µs, ≈3 orders of magnitude faster than their thin film devices. A large‐area (≈1300 mm2) imaging assembly composed of a 729‐pixel sensor array is further designed and constructed, showing excellent imaging capability thanks to its superior quality and uniformity. This opens a new possibility to use the high‐quality perovskite single‐crystal‐based devices for more advanced imaging sensors.
A low‐temperature‐gradient crystallization (LTGC) method is developed to fabricate high‐quality perovskite CH3NH3PbBr3 single‐crystals with high carrier mobility, long carrier lifetime, ultralow trap‐state density, and superior uniformity. Meanwhile, its application in photosensors gives superior detectivity as high as 6 × 1013 Jones and response speed is as fast as 40 μs. A large‐area (≈1300 mm2) imaging assembly composed of a 729‐pixel sensor array is further designed and constructed, showing excellent imaging capability thanks to its superior quality.
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•The ultrastable 1T-MoS2 was successfully achieved via a gentle two-stage solvothermal strategy.•The formation of sulfur vacancies is critical to promote the transformation of 2H to ...1T phase.•Nearly 100 % 1T-MoS2 was obtained, and it remained highly stable in air even for 360 days.•The 1T-MoS2 showed superior sorption capacity, stability and recyclability for removal of Cr(VI).
Metallic 1T phase of MoS2 (1T-MoS2) has aroused great concern for decontamination of heavy metal ions from water. Herein, ultrastable 1T-MoS2 was successfully achieved via a gentle two-stage solvothermal strategy utilizing water and ethanol as solvent for efficient removal of Cr(VI). Notably, nearly 100 % 1T-MoS2 was obtained, and it remained highly stable in air even for 360 days. Electron paramagnetic resonance analysis showed that sulfur vacancies were in situ formed on the 1T/2H mixed phase MoS2 (M-MoS2) under the induction of ethanol, which is critical to promote the transformation of 2H to 1T phase. Molecular dynamic simulation revealed that there was strong interaction between ethanol and MoS2 surface, which could decrease the total energy of MoS2 for strengthening stability of 1T phase. Moreover, 1T-MoS2 shows superior sorption capacity (200.3 mg·g−1) for removal of Cr(VI), twice more than that of M-MoS2 and 2H phase MoS2 under the same condition. Significantly, the stable phase structure of 1T-MoS2 and chromium adsorption capacity still remained even after five cycles of chromium adsorption. The study of Cr(VI) adsorption mechanism revealed that the chromium adsorption was attributed to the undercoordinated Mo(IV) as active site and coupled with redox reaction during removal process.
Epithelial-mesenchymal transition (EMT) contributes to tumor invasion and metastasis in many cancers and correlates highly with the acquisition of cancer stem cell (CSC) characteristics. EMT also ...correlates with changes in specific microRNAs (miRNAs) that have already been integrated into tumorigenic programs as either oncogenes or tumor suppressor genes. Here, we show that miR-7, which was downregulated in breast CSCs (BCSCs) isolated from the human MCF-7 and MDA-MB-231 cell lines, inhibited cell invasion and metastasis, decreased the BCSC population and partially reversed EMT in MDA-MB-231 cells by directly targeting the oncogene, SETDB1. The conspicuous epigenetic transition induced by miR-7 overexpression was found not only in MDA-MB-231 cells but also in BCSC xenograft tumors. MiR-7 inhibited the metastasis of BCSCs in lungs, kidneys, and adrenal glands of NOD/SCID mice. ChIP-polymerase chain reaction result suggested that the SETDB1 induced STAT3 expression by binding to the promoter of STAT3. MiR-7-mediated downregulation of SETDB1 resulted in the suppression of STAT3, which led to the downregulation of c-myc, twist, and mir-9. In addition, the downregulation of miR-7 in BCSCs may be indirectly attributed to lincRNA HOTAIR by modulating the expression of HoxD10 that promotes the expression of miR-7. These findings demonstrate that miR-7 was a tumor suppressor and that the overexpression of miR-7 might serve as a good strategy for treating highly invasive breast cancer.
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With their excellent optoelectronic properties, the practical application of single-crystalline organolead halide perovskite materials is now limited by the lack of a method to ...prepare high-quality perovskite single crystals in large dimension. Herein, we report our development of a low-temperature-gradient crystallization (LTGC) method for high-quality CH3NH3PbBr3 (MAPbBr3) perovskite single crystals with lateral dimension as large as two inches. The theoretical analysis suggests that a small temperature gradient should be used to restrain the growth condition, particularly the solution concentration, within the optimal single-crystal-growth (OSCG) zone. The solubility curve as a function of temperature reveals a sharp turning point at ∼60 °C, across which the first-order solubility derivative (dC/dT) shows very different behaviors: below this temperature, the dC/dT changes dramatically as the temperature increases, while above this temperature, the dC/dT enters a plateau where further temperature change has little effect on the derivative, meaning that one can attain both a substantial crystal growth rate and crystallization yield below this temperature. Utilizing this discovery, a MAPbBr3 single crystal as large as 47 × 41 × 14 mm is obtained with high quality via the LTGC method. The single crystal exhibits the best optoelectronic quality among all MAPbBr3 materials reported in the literature, including the best trap state density, mobility, carrier lifetime, and diffusion length. These superior optoelectronic properties are further transferred into a high-performance planar photodetector. The device exhibits high operational stability, high external quantum efficiency (13,453%), excellent detectivity as high as 8 × 1013 Jones, and a fast response speed as quick as 15.8 μs. To our knowledge, both the detectivity and the response speed are the best among all MAPbBr3 devices reported to date. The unique synthesis method and excellent crystalline quality of the perovskite single crystals make them promising candidates for the next generation of optoelectronic devices.
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•N-doped activated carbon supported Ni catalyst was simply synthesized by a two-step calcination method.•N doping content and type in activated carbon have important influence on ...catalytic hydrogenation activity of Ni/NAC.•Highly active and selective H2-hydrogenation/transfer hydrogenation of furfural was studied under mild conditions.•The catalyst can be reutilized during successive catalytic cycles.•The performance enhancement mechanism has been discussed on the basis of the experimental results.
In this work, N-doped activated carbon supported metallic nickel (Ni/NAC) catalysts were fabricated by two-step calcination method in N2 atmosphere for liquid-phase hydrogenation of furfural (FAL). It was found that the pyrolysis temperature and amount of melamine as N doping source have important influence on N doping content and type in activated carbon (AC) support, resulting in the subsequently formed Ni nanoparticles on N-doped AC with different sizes and thus affording different catalytic hydrogenation activities. The results demonstrated that using N-doped AC with 1.0g melamine at 1073K in N2 atmosphere as support, the obtained Ni/NAC at 873K in N2 atmosphere with Ni nanoparticle sizes of ∼13.1nm (denoted as Ni/NAC-1-1073) exhibits a N doping content of 3.65at.% and a surface area of 561.2m2g−1 with a microporous structure. As catalyst for FAL hydrogenation, Ni/NAC-1-1073 demonstrated the best catalytic performance among all investigated catalysts, achieving almost 100% selectivity of tetrahydrofurfuryl alcohol (THFOL) with a complete FAL conversion at 353K after 3h reaction, while only 76.7% selectivity of THFOL with a FAL conversion of 86.4% was obtained using Ni/AC catalyst without N doping under the identical experimental conditions. Furthermore, it was found that almost 100% conversion of FAL to furfural alcohol (FOL) can be reached by transfer hydrogenation pathway in 2-proponal solvent using Ni/NAC-1-1073 at 413K after 5h reaction, whereas Ni/AC without N doping can only afford 30.2% conversion of FAL to FOL under the same conditions. The superior catalytic performance of Ni/NAC-1-1073 could be ascribed to a synergistic effect of nanosized Ni providing catalytic active sites, suitable N doping content and type in AC to promote catalytic performance, and advantageous structure characteristics of high surface area and porous structure favourable for the exposure of catalytic active sites and mass transport.
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