Coal-based graphene quantum dots(GQDs) were successfully produced via a one-step chemical synthesis from six different coal ranks, from which two superhigh organic sulfur(SHOS) coals were selected as natural S-doped c...Coal-based graphene quantum dots(GQDs) were successfully produced via a one-step chemical synthesis from six different coal ranks, from which two superhigh organic sulfur(SHOS) coals were selected as natural S-doped carbon sources for the preparation of S-doped GQDs. The effects of coal properties on coal-based GQDs were analyzed by means of high-resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, X-ray photoelectron spectroscopy(XPS), ultraviolet-visible(UV-Vis) absorption spectroscopy, and fluorescence emission spectra. It was shown that all coal samples can be used to prepare GQDs, which emit bluegreen and blue fluorescence under ultraviolet light. Anthracite-based GQDs have a hexagonal crystal structure without defects, the largest size, and densely arranged carbon rings in their lamellae; the highrank bituminous coal-based GQDs are relatively reduced in size, with their hexagonal crystal structure being only faintly visible; the low-rank bituminous coal-based GQDs are the smallest, with sparse lattice fringes and visible internal defects. As the metamorphism of raw coals increases, the yield decreases and the fluorescence quantum yield(QY) initially increases and then decreases. Additionally, the surface of GQDs that were prepared using high-rank SHOS coal(high-rank bituminous coal) preserves rich sulfur content even after strong oxidation, which effectively adjusts the bandgap and improves the fluorescence QY. Thus, high-rank bituminous coal with SHOS content can be used as a natural S-doped carbon source to prepare S-doped GQDs, extending the clean utilization of low-grade coal.展开更多
An international opening ceremony to commemorate the establishment of the Satellite Assembly Integration&Test(AIT)facility was held in Beijing on March16,2018.The China National Space Administration(CNSA)Satellite...An international opening ceremony to commemorate the establishment of the Satellite Assembly Integration&Test(AIT)facility was held in Beijing on March16,2018.The China National Space Administration(CNSA)Satellite Assembly Integration&Test Center was established at the same time in the China Academy of Space Technology(CAST).展开更多
目的再评价肺静脉隔离(PVI)联合肾交感神经消融术(RDN)治疗心房颤动(以下简称房颤)合并高血压的系统评价。方法计算机检索PubMed、Cochrane Library、Web of Science、万方数据知识服务平台、中国知网、维普网发表的PVI联合RDN治疗房颤...目的再评价肺静脉隔离(PVI)联合肾交感神经消融术(RDN)治疗心房颤动(以下简称房颤)合并高血压的系统评价。方法计算机检索PubMed、Cochrane Library、Web of Science、万方数据知识服务平台、中国知网、维普网发表的PVI联合RDN治疗房颤合并高血压的系统评价,检索时限均为建库至2022-03-31。由两名研究员严格按照文献纳入与排除标准独立筛选和提取资料,然后采用PRISMA声明、AMSTAR2量表和GRADE方法分别评价纳入文献的报告质量、方法学质量和结局指标的证据质量。结果9篇文献的报告质量平均得分为16.5分,其中最高分22.0分、最低分11.0分;其中高质量报告1篇,中等质量报告5篇,低质量报告3篇。4篇文献的方法学质量等级为低质量,5篇文献的方法学质量等级为极低质量。9篇文献的结局指标共27个证据体,其中高质量证据体2个(7.4%),中等质量证据体6个(22.2%),低质量证据体14个(51.9%),极低质量证据体5个(18.5%)。系统评价结果显示,试验组患者房颤复发率低于对照组(P<0.05)(证据等级为低、中等、高)。试验组患者诊室收缩压、诊室舒张压降低幅度均大于对照组(P<0.05)(证据等级为低、中等);试验组患者动态收缩压、动态舒张压降低幅度均大于对照组(P<0.05)(证据等级为极低)。试验组与对照组并发症发生率比较,差异无统计学意义(P>0.05)(证据等级为极低、低、中等)。试验组患者估算肾小球滤过率(eGFR)高于对照组(P<0.05)(证据等级为低)。试验组患者左心室舒张末期内径(LVEDD)、左心室质量指数(LVMI)下降幅度大于对照组(P<0.05)(证据等级为极低)。结论该研究纳入的系统评价报告质量较高,但其结局指标证据质量偏低。PVI联合RDN可有效降低房颤合并高血压患者术后房颤复发率,提高患者降压效果,且安全性较高。展开更多
基金supported by the National Natural Science Foundation of China (grant No. 41172146)National Key Basic Research Program of China (grant No. 2014CB238905)
文摘Coal-based graphene quantum dots(GQDs) were successfully produced via a one-step chemical synthesis from six different coal ranks, from which two superhigh organic sulfur(SHOS) coals were selected as natural S-doped carbon sources for the preparation of S-doped GQDs. The effects of coal properties on coal-based GQDs were analyzed by means of high-resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, X-ray photoelectron spectroscopy(XPS), ultraviolet-visible(UV-Vis) absorption spectroscopy, and fluorescence emission spectra. It was shown that all coal samples can be used to prepare GQDs, which emit bluegreen and blue fluorescence under ultraviolet light. Anthracite-based GQDs have a hexagonal crystal structure without defects, the largest size, and densely arranged carbon rings in their lamellae; the highrank bituminous coal-based GQDs are relatively reduced in size, with their hexagonal crystal structure being only faintly visible; the low-rank bituminous coal-based GQDs are the smallest, with sparse lattice fringes and visible internal defects. As the metamorphism of raw coals increases, the yield decreases and the fluorescence quantum yield(QY) initially increases and then decreases. Additionally, the surface of GQDs that were prepared using high-rank SHOS coal(high-rank bituminous coal) preserves rich sulfur content even after strong oxidation, which effectively adjusts the bandgap and improves the fluorescence QY. Thus, high-rank bituminous coal with SHOS content can be used as a natural S-doped carbon source to prepare S-doped GQDs, extending the clean utilization of low-grade coal.
文摘An international opening ceremony to commemorate the establishment of the Satellite Assembly Integration&Test(AIT)facility was held in Beijing on March16,2018.The China National Space Administration(CNSA)Satellite Assembly Integration&Test Center was established at the same time in the China Academy of Space Technology(CAST).
文摘目的再评价肺静脉隔离(PVI)联合肾交感神经消融术(RDN)治疗心房颤动(以下简称房颤)合并高血压的系统评价。方法计算机检索PubMed、Cochrane Library、Web of Science、万方数据知识服务平台、中国知网、维普网发表的PVI联合RDN治疗房颤合并高血压的系统评价,检索时限均为建库至2022-03-31。由两名研究员严格按照文献纳入与排除标准独立筛选和提取资料,然后采用PRISMA声明、AMSTAR2量表和GRADE方法分别评价纳入文献的报告质量、方法学质量和结局指标的证据质量。结果9篇文献的报告质量平均得分为16.5分,其中最高分22.0分、最低分11.0分;其中高质量报告1篇,中等质量报告5篇,低质量报告3篇。4篇文献的方法学质量等级为低质量,5篇文献的方法学质量等级为极低质量。9篇文献的结局指标共27个证据体,其中高质量证据体2个(7.4%),中等质量证据体6个(22.2%),低质量证据体14个(51.9%),极低质量证据体5个(18.5%)。系统评价结果显示,试验组患者房颤复发率低于对照组(P<0.05)(证据等级为低、中等、高)。试验组患者诊室收缩压、诊室舒张压降低幅度均大于对照组(P<0.05)(证据等级为低、中等);试验组患者动态收缩压、动态舒张压降低幅度均大于对照组(P<0.05)(证据等级为极低)。试验组与对照组并发症发生率比较,差异无统计学意义(P>0.05)(证据等级为极低、低、中等)。试验组患者估算肾小球滤过率(eGFR)高于对照组(P<0.05)(证据等级为低)。试验组患者左心室舒张末期内径(LVEDD)、左心室质量指数(LVMI)下降幅度大于对照组(P<0.05)(证据等级为极低)。结论该研究纳入的系统评价报告质量较高,但其结局指标证据质量偏低。PVI联合RDN可有效降低房颤合并高血压患者术后房颤复发率,提高患者降压效果,且安全性较高。
