Quantitative chemical derivatization technique in time-of-flight secondary ion mass spectrometry for surface amine groups on plasma-polymerized ethylenediamine film

A chemical derivatization technique in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been developed to quantify the surface density of amine groups of plasma-polymerized ethylenediamine thin film deposited on a glass surface by inductively coupled plasma chemical vapor deposition. Chemical tags of 4-nitrobenzaldehyde or pentafluorobenzaldehyde were hybridized with the surface amine groups and were detected in TOF-SIMS spectra as characteristic molecular secondary ions. The surface amine density was controlled in a reproducible manner as a function of deposition plasma power and was also quantified using UV-visible spectroscopy. A good linear correlation was observed between the results of TOF-SIMS and UV-visible measurements as a function of plasma power. This shows that the chemical derivatization technique in TOF-SIMS analysis would be useful in quantifying the surface density of specific functional groups that exist on the organic surface.     

Fullerene-functionalized gold nanoparticles: electrochemical and spectroscopic properties

Fullerene (C(60))-tethered gold nanoparticles were synthesized by the coupling of the fullerene molecules with peripheral amine moieties on the particle surface. The particle composition was determined by thermogravimetric analysis and FT-IR spectroscopy. The resulting particles exhibited unique optical and electrochemical properties. UV-visible measurements showed that the C(60) characteristic absorption remained practically invariant whereas the fluorescence demonstrated rather drastic enhancement of emission efficiency as compared to the behaviors of C(60) monomers. Tethering of C(60) on the particle surface has virtually no effect on the particle molecular capacitance when C(60) is in neutral state, whereas when C60 is electroreduced, the particle effective capacitance increases drastically, reflected in the quantized capacitance charging measurements. The strong affinity of C(60) to amine moieties was also exploited to assemble multilayers of C(60) and gold particle nanocomposite structures. Quartz crystal microbalance measurements showed quite efficient adsorption of C(60) and particles up to two repeated cycles. However, the voltammetric responses of the surface-confined C(60) and gold particle composite structures were found to be complicated by the inaccessibility of electrolyte counterions due to the compact nature of the surface assemblies.     

Physicochemical characteristics of waste sea shells for acid gas cleaning absorbent

The properties of waste shells, which cause pollution problems, are investigated in Southern beach, Korea. The absorbent surface area was affected by the contaminant gas removal efficiency of the waste shell absorbents, pore structures, absorbent deliquescence and hygroscopicity during the contaminant gas reaction. The BET surface area of calcination/hydration waste shell and limestone samples was increased by hydration in isothermal conditions. The absorption rate with acid gas is predicted by apparatus for measuring the hydration rate. The BET surface area of waste shell samples hydrated at 90 ‡C isothermal condition was greatly increased. And pore size distribution and diameter were increased after calcination/hydration reaction. Waste seashells can be regarded as a good absorbent for removing acid gases. Therefore, the recycling of waste seashells as a substitute for limestone would be profitable. Key words:Waste Shell, Absorbent, Hydration Rate, Flue Gas Desulfurization This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

Numerical analysis of the effect of injection pressure variation on free spray and impaction spray characteristics

Compression ignition direct injection diesel engines employed a high pressure injection system have been developed as a measure to improve a fuel efficiency and reduce harmful emissions. In order to understand the effects of the pressure variation, many experimental works have been done, however there are many difficulties to get data in engine condition.     

Fast consolidation of a nanocrystalline Al2O3 reinforced 3.7Fe0.54Cr0.18Al0.26Si0.016 composite from mechanical synthesized powder through pulsed current activated heating

Nanopowders of Fe_0.54Cr_0.18Al_0.26Si_0.016 and Al₂O₃ were synthesized from Fe₂O₃, Cr, Si, and Al powders using high-energy ball milling. A high-density nanocrystalline 3.7Fe_0.54Cr_0.18Al_0.26Si_0.016-Al₂O₃ composite was consolidated with mechanically synthesized powders of Al₂O₃ and 3.7Fe_0.54Cr_0.18Al_0.26Si_0.016-Al₂O₃ through a pulsed current activated sintering (PCAS) method within 1 min. The hardness of the composite and the average grain sizes of Al₂O₃ and Fe_0.54Cr_0.18Al_0.26Si_0.016 were investigated.     

Antioxidant and anti-adipogenic activities of persimmon tannins

Soluble and insoluble tannins from 5 different types of persimmon-unripe, astringent Cheongdobansi (CU); red-ripe Cheongdobansi (CR); unripe, astringent Daebong (DU); red-ripe Daebong (DR); and unripe, non-astringent Fuyu (FU)-were prepared. The antioxidant activity of the tannins was determined by measuring the DPPH radical scavenging activity (RSA), ABTS RSA, and reducing power. The strongest DPPH RSA and reducing power were found in the soluble tannins from CU. Soluble tannins from CR, CU, and DU at a concentration of 1,000 μg/mL scavenged most of the ABTS radicals. Approximately 83 and 42% suppression of adipogenesis in 3T3-L1 cells were observed in the 100 μg/mL treatments of the soluble tannins from CU and CR, respectively. Soluble tannins showed relatively higher antioxidant and anti-adipogenic activities than insoluble tannins. These results demonstrate that soluble and insoluble persimmon tannins showed different antioxidant and anti-adipogenic activities according to persimmon types.     

Nationwide shift in CO concentration levels in urban areas of Korea after 2000

Concentrations of carbon monoxide (CO) in urban and rural air were analyzed from 16 urban roadside locations in the 7 major cities along with 5 background areas in Korea during an 11-year period (1998-2008). Because of noticeable changes in CO levels after 2000, temporal evaluation of its roadside data was carried out by grouping them into period I (1998-2000) and II (2001-2008). The mean CO values for all 16 roadside stations between the two study periods I and II were significantly different from each other (1.67 ± 0.31 ppm (I) vs. 0.95 ± 0.17 ppm (II)). This interperiod reduction in CO levels fell, if compared between different stations, in the range of 8.62-59.94% (mean = 39.8 ± 14.7%). The statistical analysis confirms that CO concentrations decreased very rapidly with the annual reduction rate of 0.093 ppm year(-1) (9.8% year(-1)). In contrast, in background areas such distinctions are no longer valid between the two periods. A line of evidence collected in this study thus suggests that the implementation of legal and technical support (e.g., upgrading of fuel quality and the natural gas vehicle supply program) should have been the effective driving forces leading to the gradual reduction in CO levels in roadside locations (10 out of 16 stations) on the peninsula.