New Analytical Method for Measuring the Atomic Weight of Neon Using Gas Chromatography with a Thermal Conductivity Detector.

The atomic weights of neon (Ne) gases were measured by gas chromatography with a thermal conductivity detector (GC-TCD). High-purity neon gas was used as the carrier and sample gases in this study, which is different from typical GC analysis. The peak signals from the GC-TCD appear when the thermal conductivity between the sample and carrier gases is different. In most gaseous molecules, the thermal conductivity has been assumed to be the same if the chemical species is the same. However, the thermal conductivity of neon gases shows different values among several manufacturers, because the relative abundance of the 22Ne isotope, which is quite large (∼10% in atmospheric neon), varies due to the mass fractionation during air separation. We identified the atomic weights of seven neon gases. Additionally, the absolute isotope ratios of all neon gases were measured using a magnetic sector type gas/mass spectrometer. The atomic weights of the seven neon gases were compared with the results obtained from GC-TCD, and the results agreed with each other within the expanded uncertainty (k = 2).

Physical and Functional Interaction between 5-HT6 Receptor and Nova-1.

5-HT6 receptor (5-HT6R) is implicated in cognitive dysfunction, mood disorder, psychosis, and eating disorders. However, despite its significant role in regulating the brain functions, regulation of 5-HT6R at the molecular level is poorly understood. Here, using yeast two-hybrid assay, we found that human 5-HT6R directly binds to neuro-oncological ventral antigen 1 (Nova-1), a brain-enriched splicing regulator. The interaction between 5-HT6R and Nova-1 was confirmed using GST pull-down and co-immunoprecipitation assays in cell lines and rat brain. The splicing activity of Nova-1 was decreased upon overexpression of 5-HT6R, which was examined by detecting the spliced intermediates of gonadotropin-releasing hormone (GnRH), a known pre-mRNA target of Nova-1, using RT-PCR. In addition, overexpression of 5-HT6R induced the translocation of Nova-1 from the nucleus to cytoplasm, resulting in the reduced splicing activity of Nova-1. In contrast, overexpression of Nova-1 reduced the activity and the total protein levels of 5-HT6R. Taken together, these results indicate that when the expression levels of 5-HT6R or Nova-1 protein are not properly regulated, it may also deteriorate the function of the other.

Analysis of trace impurities in neon by a customized gas chromatography.

Excimer lasers, widely used in the semiconductor industry, are crucial for analyzing the purity of premix laser gases for the purpose of controlling stable laser output power. In this study, we designed a system for analyzing impurities in pure neon (Ne) base gas by customized GC. Impurities in pure neon (H2 and He), which cannot be analyzed at the sub-µmol/mol level using commercial GC detectors, were analyzed by a customized pulsed-discharge Ne ionization detector (PDNeD) and a pressurized injection thermal conductivity detector using Ne as the carrier gas (Pres. Inj. Ne-TCD). From the results, trace species in Ne were identified with the following detection limits: H2, 0.378µmol/mol; O2, 0.119µmol/mol; CH4, 0.880µmol/mol; CO, 0.263µmol/mol; CO2, 0.162µmol/mol (PDNeD); and He, 0.190µmol/mol (Pres. Inj. Ne-TCD). This PDNeD and pressurized injection Ne-TCD technique thus developed permit the quantification of trace impurities present in high-purity Ne.

Effect of variation in argon content of calibration gases on determination of atmospheric carbon dioxide.

Carbon dioxide (CO(2)) is a greenhouse gas that makes by far the largest contribution to the global warming of the Earth's atmosphere. For the measurements of atmospheric CO(2) a non-dispersive infrared analyzer (NDIR) and gas chromatography are conventionally being used. We explored whether and to what degree argon content can influence the determination of atmospheric CO(2) using the comparison of CO(2) concentrations between the sample gas mixtures with varying Ar amounts at 0 and 18.6 mmol mol(-1) and the calibration gas mixtures with Ar at 8.4, 9.1, and 9.3 mmol mol(-1). We newly discovered that variation of Ar content in calibration gas mixtures could undermine accuracy for precise and accurate determination of atmospheric CO(2) in background air. The differences in CO(2) concentration due to the variation of Ar content in the calibration gas mixtures were negligible (<+/-0.03 micromol mol(-1)) for NDIR systems whereas they noticeably increased (<+/-1.09 micromol mol(-1)) especially for the modified GC systems to enhance instrumental sensitivity. We found that the thermal mass flow controller is the main source of the differences although such differences appeared only in the presence of a flow restrictor in GC systems. For reliable monitoring of real atmospheric CO(2) samples, one should use calibration gas mixtures that contain Ar content close to the level (9.332 mmol mol(-1)) in the ambient air as possible. Practical guidelines were highlighted relating to selection of appropriate analytical approaches for the accurate and precise measurements of atmospheric CO(2). In addition, theoretical implications from the findings were addressed.