The concentrations of surface functional groups on activated carbon (AC) are manipulated via heat treatment at various temperatures. The carboxyl (O−C = O) population clearly decreases at 600 °C, whereas the lactone (RO−C = O) and phenol (C−OH) populations decrease if the temperature exceeds 750 °C. Their effects on electrode capacitance, leakage current, and gas evolution are systematically investigated in 1 M tetraethylammonium tetrafluoroborate/propylene carbonate electrolyte. The assembled symmetric supercapacitors are also subjected to an aging test, where the cells are held at 2.5 V and 70 °C. The decreased functional group populations significantly reduce gassing and improve the cell durability; the mechanisms are explored using electrochemical impedance spectroscopy and postmortem SEM. Nevertheless, the AC surface area drops dramatically at 850 °C, resulting in a considerable reduction in capacitance. A rational control of heat-treatment temperature is critical for obtaining AC with balanced supercapacitor performance.

This study demonstrates that DNA barcoding (i.e. reference databasing, tissue-direct PCR and molecular analysis), especially the trnL-F region, is an efficient tool to identify field gametophytes, and has considerable potential in exploring the ecology of fern gametophytes.

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Primulina scutellifolia is described as a new species from Khanh Hoa Province, southern Central Vietnam. It is distinct in the genus in having scutellate leaves that make it a highly potential ornamental plant. The new species looks like P. annamensis in general shapes, sizes and colours of habit, inflorescence, flower, and leaf but is distinguishable by adaxially glabrous and abaxially strigose leaves with serrate margins, scutellate leaf blade and appressed downwards tomentose petiole, sparsely glandular hairs on apical 1/2 of the gynoecium and trapeziform one-lipped stigma with slightly emarginated apex.

Three new species (Calymmodon concinnus, Oreogrammitis parvula, Xiphopterella parva), and seven new records (Dasygrammitis brevivenosa, Oreogrammitis sinohirtella, Radiogrammitis beddomeana, R. jagoriana, Scleroglossum pyxidatum, S. sulcatum and Themelium halconense) of grammitid ferns (Polypodiaceae) are reported for the flora of Vietnam, mostly from newly collected specimens. We provide detailed morphological descriptions, illustrations, ecology and distribution, and taxonomic notes for each new species. Furthermore, type information, distribution, voucher specimens and taxonomic notes are provided for each newly recorded species. A checklist including synonymy and a key to Vietnamese grammitid ferns are also given.

BackgroundSapria is a distinctive and narrowly host-specific holoparasitic genus belonging to the Rafflesiaceae. Sapria himalayana, rare throughout its range from NE India, SW China, Thailand to Vietnam, is a little-understood species first recorded for Vietnam in 1959, and only recollected there over half a century later in February 2017. This has facilitated an assessment of its taxonomic identity and our understanding of its morphology and natural history aspects.ResultsSix populations of Sapria at Vietnam’s Tuyền Lâm Lake, and another two populations at the Nam Ban Protection Forest and the Cam Ly area were found, in an area of about 20 km in radius. Previously documented size attributes, morphological details and colour patterns allowed clear identification of the Vietnamese taxon as Sapria himalayana f. albovinosa. A full description of the species for Vietnam is provided. Past authors have distinguished the sexes by column form and structure, colour of the upper disk, details of the inner surface of the perigone tube, and presence of ovarial chambers below the column in the female. We present additional observations that male flowers consistently have more steeply held perigone lobes than females, in which the lobes were more spread out at wider angles in fully open flowers, and that males have a much lower cupule than females. The latter difference, especially, appears to be useful for quick determination of the sex even in the advanced floral bud stage. The host plant was the lianescent Tetrastigma laoticum (Vitaceae), but superficially it was not possible to ascertain the clonal relationship of neighbouring host lianas. Male and female flowers were found mixed together in the same cluster from one individual liana. Potential pollinators included Calliphorid and Stratiomyid flies observed visiting open flowers.ConclusionsOur observations have added to an increased understanding of the morphology of this highly specialized parasitic life form. More than this, we have ascertained its occurrence in Vietnam, with information made available to authorities of the Lâm Đồng Province where our studies were conducted, for the sites to be specially demarcated for conservation and carefully managed tourism use.

Ionic‐liquid (IL) electrolytes, characterized by large potential windows, intrinsic ionic conductivity, low environmental hazard, and high safety, are used for micropore‐ and mesopore‐rich activated‐carbon (ACmicro and ACmeso) supercapacitors. IL electrolytes consisting of various cations [1‐ethyl‐3‐methylimidazolium (EMI+), N‐propyl‐N‐methylpyrrolidinium (PMP+), and N‐butyl‐N‐methylpyrrolidinium (BMP+)] and various anions [bis(trifluoromethylsulfonyl)imide (TFSI−), BF4−, and bis(fluorosulfonyl)imide (FSI−)] are investigated. The electrolyte conductivity, viscosity, and ion transport properties at the ACmicro and ACmeso electrodes are studied. In addition, the capacitance, rate capability, and cycling stability of the two types of AC electrodes are systematically examined and post‐mortem material analyses are conducted. The effects of IL composition on the charge–discharge capacitances of the ACmicro electrodes are more pronounced than those for the ACmeso electrodes. The FSI‐based IL electrolytes, for which electrochemical properties are cation dependent, are found to be promising. Incorporating EMI+ with FSI− results in a low electrolyte viscosity and a fast ion transport, giving rise to optimized electrode capacitance and rate capability. Replacing EMI+ with PMP+ increases the cell voltage (to 3.5 V) and maximum energy density (to 42 Wh kg−1) of the ACmicro cell at the cost of cycling stability.

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