Sample entraining multi-electrode plasma sources for atomic emission spectroscopy

Plasma sources with multiple electrodes have been developed and characterized in this research for atomic emission spectroscopy. Multi-electrode plasma sources use electrodes to shape the plasma in order to continuously entrain a sample stream in the center of hot plasma, in a manner similar to an inductively coupled plasma (ICP) source. By changing the electrode spacings, the residence time can be readily adjusted even during plasma operation. Fora 25-mm plasma length, a relatively long residence time of the analyte species (23 msec) in the plasma was calculated, indicating sufficient time for desolvation, vaporization, and atomization of the sample. For a 30-mm plasma length, the interference effect of either phosphate or aluminum on calcium emission at 393.37 nm is insignificant over the entire vertical region of the plasma. The effect of an easily ionized element (EIE) is to generally enchance Ca(II) emission in the lower regions, and to depress the emission in the higher regions in the plasma, which is in general agreement with observations in an ICP. Under an assumption of local thermal equilibrium (LTE), the Fe excitation temperature and the electron number density in the center of the plasma at 8 mm above the top of the quartz tube are 5000 K and 1.0x10¹⁵ cm⁻³ for a 30-mm plasma. When current, gas flow rate, and plasma length are varied, the spatial emission profiles reflect many of the characteristics associated with an ICP. The short term stability of the plasma with a blank solution is better than 2% (relative standard deviation). A total of less than 6 L/min of argon gas is required to operate the plasma. With the vertical 4-electrode plasma source, 4 to 5 orders of magnitude of linear dynamic range are obtained and detection limits for 12 elements are comparable to those obtained with an ICP

Dietary sodium and potassium intake of Koreans estimated using 2 different sources of their contents in foods, Food & Nutrient Database and the Korean Total Diet Study : a comparative study

Objectives: Based on the results from the Korean Total Diet Study (KTDS), the sodium (Na) and potassium (K) intake of Koreans were estimated and compared with intake estimates from the Food & Nutrient Database (FNDB), as in the Korea National Health and Nutrition Examination Survey (KNHANES) to verify the validity of these estimates. Methods: One hundred and thirty-four representative foods (RFs) covering 92.5% of the total food intake of Koreans were selected, and 228 pairs of corresponding ‘RF x representative cooking method’ were derived by reflecting the methods used mainly in terms of frequency and quantity in their cooking. RF samples were collected from three cities with a larger population size in three regions (nine cities) nationwide, and six composite samples were made for each RF, considering its regional and/or seasonal characteristics. One thousand three hundred and sixty-eight ‘RF x representative cooking method’ pair samples were prepared, and the Na and K contents were assessed using inductively coupled plasma atomic emission spectrometry (ICP-MS). The Na and K intake of the Korean population was estimated by linking the content with the food intake data from the 7th KNHANES. Results: The mean Na and K intake of Koreans were 2,807.4 mg and 2,335.0 mg per person per day, respectively. A comparison with the Na and K intake from KNHANES, including only RFs of KTDS, showed comparable results with less than 5% variation. While the contribution and ranking of food items to Na intake were similar between KNHANES and KTDS, there were differences in K intake. This was attributed to the large discrepancies in the K content of rice and coffee between KTDS results and the values in the 9th Revision of the National Food Composition Table used in KNHANES. Conclusions: The Na and K intake of Koreans estimated based on the KTDS, which performed nutrient analysis on samples prepared to a ‘table-ready’ state using foods of the representative collection, was similar and comparable with that of KNHANES. This supports the validity and usefulness of FNDB-based nutrient intake estimation at the population level. The list of nutrients studied in KTDS is expected to be expanded, allowing for intake estimation of nutrients with currently insufficient or absent information in the FNDBs in use

Swelling-activated Cl- Channels in Human Salivary Gland Acinar Cells

The role of Cl - channels in regulatory volume decrease (RVD) in human salivary gland acinar cells was examined using a whole-cell patch clamp technique. Human tissues were obtained from healthy volunteers or from patients with oromaxillofacial tumors. During the measurements, K+-free solutions were employed to eliminate contamination of whole-cell conductance by K+ currents. When the cells were exposed to a 70% hypotonic solution, outward-rectifying currents, which were not observed in the resting state, were found to have significantly increased both in human labial and parotid gland acinar cells. The amplitudes of the currents were reduced in a low Cl - bath solution. Furthermore, the addition of 100 μM 5-Nitro-2- (3-phenyl propylamino) benzoic acid (NPPB) or 100 μM 4,4'-diisothio cyanatostilbene -2,2'-disulphonic acid (DIDS), known to partially block Cl - channels, significantly inhibited these currents. Its outward-rectifying current profile, shift in reversal potential in a low Cl - bath solution and pharmacological properties suggest that this is a Ca 2+-independent, volume activated Cl - current. We conclude therefore that volume activated Cl - channels play a putative role in RVD in human salivary gland acinar cells.This work was supported by the Korea Science & Engineering Foundation (KOSEF) grant funded by Korea government(R13-2008-008-01001-0) through the Oromaxillofacial Dysfunction Research Center for the Elderly at Seoul National University

Differences in Skin Properties of Korean Women at the Initial Aging Phase

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ELK3 modulates the antitumor efficacy of natural killer cells against triple negative breast cancer by regulating mitochondrial dynamics

Background Triple negative breast cancer (TNBC) is the most lethal subtype of breast cancer due to its aggressive behavior and frequent development of resistance to chemotherapy. Although natural killer (NK) cell-based immunotherapy is a promising strategy for overcoming barriers to cancer treatment, the therapeutic efficacy of NK cells against TNBC is below expectations. E26 transformation-specific transcription factor ELK3 (ELK3) is highly expressed in TNBCs and functions as a master regulator of the epithelial-mesenchymal transition.Methods Two representative human TNBC cell lines, MDA-MB231 and Hs578T, were exposed to ELK3-targeting shRNA or an ELK3-expressing plasmid to modulate ELK3 expression. The downstream target genes of ELK3 were identified using a combined approach comprising gene expression profiling and molecular analysis. The role of ELK3 in determining the immunosensitivity of TNBC to NK cells was investigated in terms of mitochondrial fission–fusion transition and reactive oxygen species concentration both in vitro and in vivo.Results ELK3-dependent mitochondrial fission–fusion status was linked to the mitochondrial superoxide concentration in TNBCs and was a main determinant of NK cell-mediated immune responses. We identified mitochondrial dynamics proteins of 51 (Mid51), a major mediator of mitochondrial fission, as a direct downstream target of ELK3 in TNBCs. Also, we demonstrated that expression of ELK3 correlated inversely with that of Mid51, and that the ELK3-Mid51 axis is associated directly with the status of mitochondrial dynamics. METABRIC analysis revealed that the ELK3-Mid51 axis has a direct effect on the immune score and survival of patients with TNBC.Conclusions Taken together, the data suggest that NK cell responses to TNBC are linked directly to ELK3 expression levels, shedding new light on strategies to improve the efficacy of NK cell-based immunotherapy of TNBC

Stretchable PPG sensor with light polarization for physical activity-permissible monitoring

Skin-attachable sensors, which represent the ultimate form of wearable electronic devices that ensure conformal contact with skin, suffer from motion artifact limitations owing to relative changes in position between the sensor and skin during physical activities. In this study, a polarization-selective structure of a skin-conformable photoplethysmographic (PPG) sensor was developed to decrease the amount of scattered light from the epidermis, which is the main cause of motion artifacts. The motion artifacts were suppressed more than 10-fold in comparison with those of rigid sensors. The developed sensor-with two orthogonal polarizers-facilitated successful PPG signal monitoring during wrist angle movements corresponding to high levels of physical activity, enabling continuous monitoring of daily activities, even while exercising for personal health care.N