N,S-Doped activated carbon was directly prepared via a facile and cost-efficient hydrothermal reaction, followed by alkali activation of elm flower (EL)-derived biomass. The EL-derived activated carbon (ELAC) had N and S contents of 2.21 and 6.06 atom %, respectively, in addition to a high Brunauer–Emmett–Teller (BET) surface area of 2048.6 m2 g–1 and moderate pore volume of 0.88 cm3 g–1. Owing to its high BET surface area and N/S functional groups, ELAC achieved a specific capacitance of 275 F g–1 at a current density of 1 A g–1 and retained a capacitance of 216 F g–1 at 20 A g–1. In addition, a symmetric supercapacitor based on N,S-self-doped ELAC electrode provided a capacitance of 62 F g–1 at a current density of 10 A g–1, with maximum energy and power densities of 16.8 Wh kg–1 and 600 W kg–1, respectively. The capacitance retention was also high, at 87.2%, at 4 A g–1 after 5000 cycles.

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MALDI-TOF MS is utilized to perform quantitative analysis on synthetic polymers. Despite the inherent limitations of MALDI, good quantitative results have been obtained in the three sets of experiments described here. An internal standard with similar molecular properties as the analytes is introduced. Plots of relative integrated intensity ratios as a function of theoretical ratios of stoichiometry are drawn based on the results. In the case of synthetic polymer quantitative analysis, much less effort has been made compared to that of biomolecules. In industry, many polymers are in fact copolymers which take advantage of the properties of two (or more) different classes of monomer. Therefore, the reliable method of measuring the fraction of each component precisely is crucial. However, some indigenous factors of MALDI hinder the quantitative analysis on synthetic polymers. The limitations arise mainly from factors such as the homogeneity of the sample/ matrix/cationization salt spot on the target, which is considered to contribute to the notable instability of signal intensities of analytes in the spectra, the different ionization efficiencies and differences in desorption and detection of the different components which are concerned as the most critical parameter in determining the intensities of peaks in the MALDI spectra, the distribution of molecular weights of oligomer chains and subunits which causes the signal to appear more complicated in the mass spectra of polymer than the single peak in the case of biomolecules, the mass discrimination in the process of ionization, and transmission and detection which makes the intensities of the mass spectra lower both in low mass range and high mass range. Combined, these factors are believed to compromise the precision, reproducibility, and practicality with which quantitative measurement on synthetic polymers can be made.Despite the limitations, some achievement has been accomplished in quantitation of synthetic polymers by MALDI-TOF. For instance, Gardella and his coworkers [15] reported quantitative MALDI-TOF measurements of polydimethylsiloxane of two different molecular weights. Murgasova and Hercules [16] carried out the quantitative characterization of a polystyrene/polymethylstyrene blend using coupled size-exclusion chromatography and MALDI mass spectrometry. Additionally, in our previous study [17], we demonstrated the possibility of quantitative analysis of different components of a polymer sample. Two polyethylene glycols with different end-groups were regarded as different components of a simulated "polymer" through artificial mixture. The relative ion intensity ratios of two components were found to have quantitative relations with their ratios of moles.Although the work above conducted the quantitative

Tent-like nitrogen-doped carbon microcavities are elaborately designed to guide uniform lithium deposition towards stable lithium metal anodes with superior performance.

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