Greenhouse gas emission factor development for coal-fired power plants in Korea

Accurate estimation of greenhouse gas emissions is essential for developing an appropriate strategy to mitigate global warming. This study examined the characteristics of greenhouse gas emission from power plants, a major greenhouse gas source in Korea. The power plants examined use bituminous coal, anthracite, and sub-bituminous coal as fuel. The CO₂ concentration from power plants was measured using GC–FID with methanizer. The amount of carbon, hydrogen, and calorific values in the input fuel was measured using an elemental analyzer and calorimeter. For fuel analysis, CO₂ emission factors for anthracite, bituminous coal, and sub-bituminous coal were 108.9, 88.4, and 97.9 Mg/kJ, respectively. The emission factors developed in this study were compared with those for IPCC. The results showed that CO₂ emission was 10.8% higher for anthracite, 5.5% lower for bituminous coal, and 1.9% higher for sub-bituminous coal than the IPCC figures.     

Bacteria sorting by field-flow fractionation. Application to whole-cell Escherichia coil vaccine strains

Sorting and quantification of deactivated bacteria is an important way of quality control for whole-cell bacterial vaccines. In general, surface features of deactivated bacteria used for whole-cell bacterial vaccines affect the immunoresponse to bacteria-associated antigens. Enumeration of bacteria is also an important process development parameter for these vaccines. Field-flow fractionation (FFF) was previously applied to the separation of bacteria. For the first time, FFF is used for sorting bacteria strains of the same species on the basis of differences in bacterial membrane characteristics. Two FFF techniques, gravitational FFF (GrFFF) and asymmetrical flow FFF (AsFIFFF), are shown to be able to fractionate, distinguish, and quantify different deactivated Escherichia coli strains used for vaccines. E. coli can differ in the presence of fimbriae on the bacterial membrane. Fimbriae affect E. coli pathology and thus the use of E. coli for vaccines. GrFFF and AsFIFFF are able to fractionate fimbriated/ nonfimbriated cells in mixtures of different strains. While GrFFF is characterized by low cost and simplicity, As-FIFFF shows a higher performance in size fractionation with a high-speed separation. Coupled, on-line UV/visible turbidimetry yields the relative numbers of fractionated cells and sample recovery. Scanning electron microscopy and quasi-elastic light scattering are employed as uncorrelated techniques for size and morphology analysis of the E. coli strains.     

Morphology and metabolism of Ba-alginate encapsulated hepatocytes with galactosylated poly(allyl amine) and poly(vinyl alcohol) as extracellular matrices

Lactobionic acid, bearing a -galactose group, was coupled with poly(allyl amine) to provide synthetic extracellular matrices together with poly(vinyl alcohol) (PVA). The hepatocytes were encapsulated in Ba-alginate capsules with galactosylated poly(allyl amine) (GA) and PVA as extracellular matrices. From microscopic observation, it was revealed that the microcapsule prepared has a highly porous structure with interconnected pores and pore sizes ranging between 50–150 nm on both the surface and the cross-section. It was found, from the permeability experiment of microcapsules using FITC-dextrans with different molecular weights, that the capsule has a molecular weight cut off (MWCO) of 120 kDa, showing the potential that it can function as an immunoprotecting wall. The hepatocytes, cultured with GA and PVA in the core of the microcapsule, rapidly aggregated within a day, thus resulting in good metabolic functions such as albumin synthesis and ammonia removal.     

Hollow-fiber flow field-flow fractionation for whole bacteria analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

This work proposes for the first time the use of hollow-fiber flow field-flow fractionation (HF FlFFF) for improved matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOFMS) of whole bacteria. HF FlFFF has proved to be able to prepurify or fractionate different species of whole bacteria. Sample preparation by HF FlFFF gives improved spectra quality because noncellular components possibly present in the sample can be separated from the cells. When a mixture of two bacteria (Bacillus subtilis and Escherichia coli) is fractionated through HF FlFFF, MALDI/TOFMS analysis of each separated bacterial species preserves the most characteristic ion signals of the species without the presence of characteristic signals of the other species. The main advantages of HF FlFFF for MALDI/TOFMS analysis of whole bacteria are miniaturization, simplicity, and low cost of the fractionator components. This low cost makes disposable usage of the fractionator possible, thus eliminating the risk of run-to-run contamination of spectra due to sample carryover. The low fractionator volume yields bacterial fractionation on the order of a few minutes, which is comparable to MALDI/TOFMS analysis time. The small fractionation volume makes sample dilution low enough so that additional sample concentration steps are not strictly required to preserve MALDI/TOFMS detection.     

Development of high-sensitivity ion trap ion mobility spectrometry time-of-flight techniques: a high-throughput nano-LC-IMS-TOF separation of peptides arising from a Drosophila protein extract

A linear octopole trap interface for an ion mobility time-of-flight mass spectrometer has been developed for focusing and accumulating continuous beams of ions produced by electrospray ionization. The interface improves experimental efficiencies by factors of approximately 50-200 compared with an analogous configuration that utilizes a three-dimensional Paul geometry trap (Hoaglund-Hyzer, C. S.; Lee, Y. J.; Counterman, A. E.; Clemmer, D. E. Anal. Chem. 2002, 74, 992-1006). With these improvements, it is possible to record nested drift (flight) time distributions for complex mixtures in fractions of a second. We demonstrate the approach for several well-defined peptide mixtures and an assessment of the detection limits is given. Additionally, we demonstrate the utility of the approach in the field of proteomics by an on-line, three-dimensional nano-LC-ion mobility-TOF separation of tryptic peptides from the Drosophila proteome.     

A new life extension method for high cycle fatigue using micro-martensitic transformation in an austenitic stainless steel

Most of the conventional strengthening methods for metals and alloys such as work hardening, precipitation hardening, cause a decrease in ductility and are not very effective for cyclic loading. In this study, a new strengthening method, which is effective for high cycle fatigue, has been developed. The intersections of dislocations in a stainless steel are freezed by very fine martensite particles, which are supposed to suppress dislocation motion at low stress amplitudes. Fatigue life in a high cycle regime increased >60 times, and no decrease in ductility was observed in tensile tests, as compared to a work-hardened stainless steel.     

Synthesis and single-crystal structures of fully dehydrated fully Sr2+-exchanged zeolite Y (FAU) and its benzene sorption complex, |Sr37.5|[Si117Al75O384]-FAU and |Sr37.5(C6H6)33(H2O)15|[Si117Al75O384]-FAU

Single crystals of zeolite Y, |Na₇₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU, were Sr²⁺ ion exchanged and fully dehydrated to generate |Sr_37.5|[Si₁₁₇Al₇₅O₃₈₄]-FAU (crystal 1) and next, benzene adsorbed to generate |Sr_37.5(C₆H₆)₃₃(H₂O)₁₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU (crystal 2, partially dehydrated). Crystal 1 was prepared by ion exchange in a flowing stream of aqueous 0.05 M Sr(ClO₄)₂ for 3 days followed by dehydration at 673 K and 1 × 10^?6 Torr for 2 days. To prepare the benzene sorption complex (crystal 2), another dehydrated |Sr_37.5|[Si₁₁₇Al₇₅O₃₈₄]-FAU crystal was exposed to 50 Torr of benzene for 3 days at 294 K followed by evacuation for 30 min. at this temperature and 5 × 10^?5 Torr. Their structures were determined crystallographically at 100(1) K using synchrotron X-radiation in the cubic space group Fd $ \bar{3} $ m. They were refined to the final error indices R ₁/wR ₂ = 0.051/0.125 and 0.057/0.154 using 598 and 590 reflections with F _o > 4??(F _o) for crystals 1 and 2, respectively. In crystal 1, about 37.5 Sr²⁺ ions per unit cell are found at an unusually large number of crystallographically distinct positions, six. Eight Sr²⁺ ions per unit cell are at the centers of the double 6-rings (D6Rs, site I). Five additional Sr²⁺ ions are near site I. The site-I?? positions (in the sodalite cavities opposite D6Rs) are occupied by 2.5 Sr²⁺ ions per unit cell. Two Sr²⁺ ions are located at site II?? in the sodalite cavity. The remaining twenty Sr²⁺ ions are found at two nonequivalent sites II (in the supercages) with occupancies of 9 and 11 ions per unit cell, respectively. Each of these Sr²⁺ ions coordinates to three framework oxygens. In this crystal, all sites are only sparsely occupied. In crystal 2, all Sr²⁺ ions are located at four crystallographic sites and 33 benzene molecules are found at two distinct sites within the supercages. One Sr²⁺ ion is at the center of the D6R. Fifteen Sr²⁺ ions are located at site I??. The remaining 21.5 Sr²⁺ ions are found at two nonequivalent sites II with occupancies of 19 and 2.5 ions per unit cell. Nineteen benzenes lie on threefold axes in the supercages, where they interact facially with the latter 19 site-II Sr²⁺ ions; occupancy = 19 molecules/32 sites. The remaining fourteen benzene molecules are found in 12-ring planes; occupancy = 14 molecules/16 sites. Each hydrogen of these 14 benzenes is ca. 2.9 Å from six 12-ring oxygens.     

Radon exposure assessment for underground workers: a case of Seoul Subway Police officers in Korea

The objective of this study is the systematic and individual assessment of the annual effective dose due to inhaled radon for the Seoul Subway Police officers, Korea. The annual average radon concentrations were found to be in the range of 18.9-114 Bq·m(-3) in their workplaces. The total annual effective doses which may likely to be received on duty were assessed to be in the range of 0.41-1.64 mSv·y(-1). These were well below the recommended action level 10 mSv·y(-1) by ICRP. However, the effective doses were higher than subway station staff in Seoul, Korea.