Pore structure and the properties of electric double layer capacitor electrode of bamboo-derived activated carbon prepared by superheated steam

Bamboo-derived activated carbon prepared by superheated steam (BAC) exhibited performance for utilization as an electric double layer capacitor (EDLC) electrode. Pore structure and EDLC performances were investigated by comparison with phenol resin-derived activated carbon (MSP-20), which is commercially available and often used for the purpose. The nitrogen adsorption isotherm showed that BAC had a large BET-specific surface area of 1268 g/m² with a developed pore structure, especially of the mesopore, in comparison with MSP-20. It is considered that inherent ash in bamboo promoted activation, in addition to physical activation by superheated steam. Capacitance per electrode volume (C_V) was 52 F/cm³ with BAC. Because the density of BAC is high (0.78 g/cm³) compared with that of MSP-20 (0.58 g/cm³), sufficient C_V for usage was obtained, although the capacitance per electrode mass (C_M) at 5 mA/cm² itself of BAC (67 F/g) was lower than that of MSP-20 (126 F/g). With IR drop, the resistance value of BAC (9.7 Ω) was lower than that of MSP-20 (10.5 Ω). Especially, the diffusion resistance of BAC disclosed to be smaller than that of MSP-20. These results indicated that BAC produced by steam activation is a promising material with a pore structure suitable for ion transfer in EDLC.     

Evaluation of Activated Carbon-Coated Electrode in Electrostatic Precipitator and Its Regeneration for Volatile Organic Compounds Removal

Activated carbon-coated electrode was developed and applied in electrostatic precipitator to remove volatile organic compound gases simultaneously with dust particles from a contaminated air. The activated carbon coating mixture was made up of powdered activated carbon (AC), carbon black (CB), and polyvinyl acetate (PVA), and methanol was added as a solvent to control the thickness of the mixture for best coating performance. During the coating process, the Brunauer-Emmett-Teller (BET) surface decreased to 86% of the original AC while pore volume percentages of macro pore increased, compared to micro- and meso-sized pores. The adsorption isotherm of benzene, toluene, ethyl benzene, and xylene (BTEX) gases onto the original AC and AC coating mixture (AC thoroughly mixed with PVA and methanol for coating and powdered again after dry) were tested and compared to each other, and it was found that both isotherm were best fitted to Freundlich and Langmuir isotherm with the order of adsorption capacities; ethyl benzene?>?m-xylene?>?toluene?>?benzene. The difference between adsorption capacities was clearer with the absorbent AC but became little with the AC coating mixture. In removing BTEX at increasing linear velocities up to 6.7 cm/s, it appeared that the surface area of AC electrode was directly proportional to its removal rate of BTEX. The thermal desorption was applied to regenerate the AC electrode, and 200 °C was found to be most efficient for benzene desorption, but higher temperature would be required for entire BTEX gases desorption.     

Effect of polystyrene mixing on mechanical properties and structural changes in melt spinning

To increase the spinning speed of poly(trimethylene terephthalate) (PTT) fibers, polystyrene (PS) was selected as an additive polymer in the PTT matrix. Mixing of the immiscible PS with PTT led to an increase in spinning speed up to 5,500 m/min. PS was employed to improve the extensibility of the matrix PTT in the spinning process as it can prevent PTT molecular orientation. Experimental results show that the mixing of PS achieved this. The elongation at break of spun fibers increased with the amount of PS. PS addition prevented fiber orientation, especially amorphous orientation, and improved drawability, and as such, increased spinning speed up to 5,500 m/min.     

Comparing the carbon sequestration capacity of temperate deciduous forests between urban and rural landscapes in central Japan

Urbanisation is increasing tremendously in some parts of the world. Consequently, many rural forests may become depleted, although many opportunities exist for urban forests to increase. However, few studies have quantified the carbon (C) sequestration capacities of urban and rural forests in specific climatic zones. The present study compared carbon sequestration in two temperate deciduous forests located in Nagoya and Toyota, central Japan. The Nagoya University forest represented an urban forest, and a site in Toyota represented a rural forest. The urban forest at Nagoya University had comparatively smaller areas of green space and larger areas of buildings and roads. Land uses for building and road, which are typical of urban areas, result in smaller diurnal temperature ranges but higher air temperature, vapour pressure deficit, and atmospheric carbon dioxide (CO₂) concentration. The urban forest in this study exhibited higher gross ecosystem exchange (GEE), especially in the active growing season from May to September, suggesting the possible effect of CO₂ fertilisation. However, higher air temperatures caused comparatively smaller net ecosystem exchange (NEE) because of higher ecosystem respiration (RE). Although both forests functioned as CO₂ sinks at annual time scales, the rural Toyota forest site (5.43 t C ha^–1 yr^–1) had 36% higher net ecosystem production (NEP=–NEE; the negative sign indicates uptake by the forest ecosystem from the atmosphere) than that at the urban forest. The higher normalised respiration (i.e., RE/GPP ratio; GPP=–GEE where GPP represents gross primary production) at the Nagoya University forest might be attributable to factors associated with the degree of urbanisation. Thus, in temperate forests, factors associated with urbanisation may reduce the atmospheric carbon sink function by accelerating respiration. This is an issue of global interest, as many countries are experiencing rapid urbanisation.     

Metabolic Profiling of Glucosinolates, Anthocyanins, Carotenoids, and Other Secondary Metabolites in Kohlrabi (Brassica oleracea var. gongylodes)

We profiled and quantified glucosinolates, anthocyanins, carotenoids, and other secondary metabolites in the skin and flesh of pale green and purple kohlrabis. Analysis of these distinct kohlrabis revealed the presence of 8 glucosinolates, 12 anthocyanins, 2 carotenoids, and 7 phenylpropanoids. Glucosinolate contents varied among the different parts and types of kohlrabi. Glucoerucin contents were 4-fold higher in the flesh of purple kohlrabi than those in the skin. Among the 12 anthocyanins, cyanidin 3-(feruloyl)(sinapoyl) diglucoside-5-glucoside levels were the highest. Carotenoid levels were much higher in the skins than the flesh of both types of kohlrabi. The levels of most phenylpropanoids were higher in purple kohlrabi than in pale green ones. trans-Cinnamic acid content was 12.7-fold higher in the flesh of purple kohlrabi than that in the pale green ones. Thus, the amounts of glucosinolates, anthocyanins, carotenoids, and phenylpropanoids varied widely, and the variations in these compounds between the two types of kohlrabi were significant.     

Application of electrospun polyurethane web to breathable water-proof fabrics

Electrospun web may possibly be widely applied to protective garments or specialty textiles due to its high level of protection as well as comfort. Of particular interest in this study is to develop waterproof-breathable fabric by applying electrospun web of polyurethane directly onto the substrate fabric. The optimal electrospinning condition was examined with regards to the concentration, applied voltage and tip-to-collector distance. Solvent-electospinning of polyurethane was performed at the optimum condition, using N,N-dimethylacetamide as solvent. The thickness of 0.02 mm of electrospun web was applied onto the polyester/nylon blended fabric. For comparison, the polyester/nylon fabrics were coated with 0.02 mm thickness of polyurethane resin membranes adopting four different conditions. The electrospun PU web/fabric was compared to resin coated fabrics in terms of water-proof and breathable properties. The electrospun web applied fabric showed higher air permeability, vapor transmission, and thermal insulation properties than resin coated fabrics, which can be translated as greater comfort sensation of electrospun applied fabrics. However, water resistance value of electrospun web applied fabric did not reach that of resin coated fabrics.     

Preparation of poly(vinyl alcohol)/ZrO2 composite nanofibers via co-axial electrospinning with higher ZrO2 particle content

Poly(vinyl alcohol) (PVA)/zirconium oxide (ZrO₂) composite nanofibers with a skin-core structure were prepared and the effect of ZrO₂ particle content on uniform web formation was investigated. The optimized polymer concentration, tip to collector distance, and applied voltage for electrospinning were 11 wt%, 12 cm, and 20 kV, respectively. Skin-core PVA/ZrO₂ composite nanofibers containing up to 12 wt% ZrO₂ were successfully prepared, but it was difficult to obtain PVA/ZrO₂ composite nanofiber webs via conventional electrospinning. Increasing the amount of ZrO₂ caused the morphology of the PVA/ZrO₂ composite nanofibers to become a non-uniform nanoweb with irregular nanofiber diameters. While it was difficult to obtain a uniform nanofiber web containing a content of ZrO₂ over 6 wt% for conventional electrospinning, a more uniform nanofiber web could be obtained at up to 9 wt% ZrO₂ using a skin-core dual nozzle. More uniform webs could also be obtained when ZrO₂ was in the skin rather than the core.     

Low expression of mitofusin 1 is associated with mitochondrial dysfunction and apoptosis in porcine somatic cell nuclear transfer embryos

Mitochondria are necessary for the transition from oocyte to embryo and for early embryonic development. Mitofusin 1 is the main mediator of mitochondrial fusion and homeostasis. We investigated Mitofusin 1 expression levels in porcine somatic cell nuclear transfer (SCNT) embryos. The rate of blastocyst formation in SCNT embryos was reduced significantly compared with that of parthenogenetic activation embryos. SCNT embryos showed significantly decreased Mitofusin 1 expression and mitochondrial membrane potential, while exhibiting increased reactive oxygen species and apoptosis. Mitochondrial functional changes were observed in the SCNT embryos and may be correlated with low levels of Mitofusin 1 to negatively affect development.     

New Cyclic Cystine Bridged Peptides from the Sponge Suberites waedoensis

Two new peptides, chujamides A (1) and B (2), were isolated from the marine sponge Suberites waedoensis, which was collected from Korean waters. Based upon the results of the combined spectroscopic analyses, the structures of these compounds were determined to be proline-riched and cyclic cystine bridged dodeca- and undecapeptides. The absolute configurations of all amino acid residues were determined to be l by advanced Marfey’s analysis. The new compounds exhibited weak cytotoxicities against A549 and K562 cell-lines, and compound 2 also demonstrated moderate inhibitory activity against Na⁺/K⁺-ATPase.