Improvement in precision of extremely low 236U/238U isotope ratio determination by using mass spectrometer with narrow dynamic range

Abstract. Plasma waves are important observational targets for scientific missions investigating space plasma phenomena. Conventional fast Fourier transform (FFT)-based spectrum plasma wave receivers have the disadvantages of a large size and a narrow dynamic range. This paper proposes a new type of FFT-based spectrum plasma wave receiver that overcomes the disadvantages of conventional receivers. The receiver measures and calculates the whole spectrum by dividing the observation frequency range into three bands: bands 1, 2, and 3, which span 1 Hz to 1 kHz, 1 to 10 kHz, and 10 to 100 kHz, respectively. To reduce the size of the receiver, its analog section was realized using application-specific integrated circuit (ASIC) technology, and an ASIC chip was successfully developed. The dimensions of the analog circuits were 4.21 mm  ×  1.16 mm. To confirm the performance of the ASIC, a test system for the receiver was developed using the ASIC, an analog-to-digital converter, and a personal computer. The frequency resolutions for bands 1, 2, and 3 were 3.2, 32, and 320 Hz, respectively, and the average time resolution was 384 ms. These frequency and time resolutions are superior to those of conventional FFT-based receivers.

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Chromosome segregation fidelity is controlled by small changes in phospho-occupancy at the kinetochore-microtubule interface

10.1101/2021.02.16.431549 ◽

2021 ◽

Author(s):

Thomas J. Kucharski ◽

Rufus Hards ◽

Kristina M. Godek ◽

Scott A. Gerber ◽

Duane A. Compton

Keyword(s):

Error Correction ◽

Chromosome Segregation ◽

Dynamic Range ◽

High Sensitivity ◽

Cyclin B1 ◽

Quantitative Mass Spectrometry ◽

Kinetochore Protein ◽

Microtubule Attachment ◽

Different Types ◽

Narrow Dynamic Range

SummaryKinetochore protein phosphorylation promotes the correction of erroneous microtubule attachments to ensure faithful chromosome segregation during cell division. Determining how phosphorylation executes error correction requires an understanding of whether kinetochore substrates are completely (i.e. all-or-none) or only fractionally phosphorylated. Using quantitative mass spectrometry (MS), we measured phospho-occupancy on the conserved kinetochore protein Hec1 (NDC80) that directly binds microtubules. None of the positions measured exceeded ∼50% phospho-occupancy, and the cumulative phospho-occupancy changed by only ∼20% in response to changes in microtubule attachment status. The narrow dynamic range of phospho-occupancy is maintained by ongoing phosphatase activity. Further, both Cdk1-Cyclin B1 and Aurora kinases phosphorylate Hec1 to enhance error correction in response to different types of microtubule attachment errors. Thus, networks of kinases and phosphatases maintain low inherent phospho-occupancy to promote microtubule attachment to kinetochores while providing for high sensitivity of kinetochore-microtubule attachments to very small changes in phospho-occupancy to ensure high mitotic fidelity.

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A STUDY ON CARBON ISOTOPE OF CO2 AND CH4 IN WESTERN DIENG PLATEU BY GAS CHROMATOGRAPHY- ISOTOPE RATIO MASS SPECTROMETER (GC-IRMS)

Indonesian Journal of Chemistry ◽

10.22146/ijc.21832 ◽

2010 ◽

Vol 5 (1) ◽

pp. 11-14

Author(s):

Hanik Humaida

Keyword(s):

Gas Chromatography ◽

Carbon Isotope ◽

Mass Spectrometer ◽

Isotope Ratio ◽

Isotope Analysis ◽

Ionization Detector ◽

Volcanic Gas ◽

Porapak Q ◽

Flame Ionization ◽

Isotope Ratio Mass Spectrometer

The carbon isotope can be used to evaluate volcanism phenomenon of volcano. The study of carbon isotope of CO2 and CH4 was carried out in western Dieng Plateau by mass-spectrometer. Before analysis, sampel was separated by gas chromatography using a Porapak-Q column and a FID (Flame Ionization Detector) detector. The gas was oxidized by copper oxide at 850oC before being ionized in mass-spectrometer for isotope analysis. The CO2 content in Candradimuka crater (-4.10 O/OO), indicated that the gas may be as volcanic gas. The other CO2 from Sumber and western Gua Jimat, had isotope value of -10.05 and -12.07 O/OO, respectively, indicating contamination from crustal and subduction material. The carbon isotope of CH4 gas from Pancasan village was -63.42 O/OO, that may be categorized as biogenic gas. Keywords: isotope, CO2, CH4, Dieng.

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