scholarly journals Technical note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

2021 ◽  
Vol 18 (2) ◽  
pp. 729-737
Author(s):  
Philipp A. Nauer ◽  
Eleonora Chiri ◽  
Thanavit Jirapanjawat ◽  
Chris Greening ◽  
Perran L. M. Cook
Keyword(s):  
Carbon Monoxide ◽  
Linear Increase ◽  
Technical Note ◽  
Mixing Ratios ◽  
Long Term Storage ◽  
Large Numbers ◽  
Zero Order Reaction ◽  
Low Volume ◽  
Proposed Modification

Abstract. Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete samples of low volume. While commercial sampling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace-gas release, but contamination was still substantial, with H2 and CO mixing ratios in air samples increasing by a factor of 3 and 10 after 30 d of storage in conventional 12 mL Exetainers. All tested materials showed a near-linear increase in H2 and CO mixing ratios, indicating a zero-order reaction and material degradation as the underlying cause. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose modifying Exetainers by closing them with a silicone plug to minimise contamination and sealing them with a stainless-steel bolt and O-ring as a secondary diffusion barrier for long-term storage. Such modified Exetainers exhibited stable mixing ratios of H2 and CH4 exceeding 60 d of storage at atmospheric and elevated (10 ppm) mixing ratios. The increase of CO was still measurable but was 9 times lower than in conventional Exetainers with treated septa; this can be corrected for due to its linearity by storing a standard gas alongside the samples. The proposed modification is inexpensive, scalable and robust, and thus it enables reliable storage of large numbers of low-volume gas samples from remote field locations.

scholarly journals Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

2020 ◽  
Author(s):  
Philipp A. Nauer ◽  
Eleonora Chiri ◽  
Thanavit Jirapanjawat ◽  
Chris Greening ◽  
Perran L. M. Cook
Keyword(s):  
Carbon Monoxide ◽  
Technical Note ◽  
Trace Gas ◽  
Rubber Material ◽  
Long Term Storage ◽  
Large Numbers ◽  
Low Volume ◽  
Proposed Modification ◽  
Term Storage

Abstract. Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete samples of low volume. While commercial sampling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace gas release, but contamination was still substantial, with H2 and CO concentrations in air samples increasing by a factor of 3 and 10 after 30 days of storage in conventional 12 mL Exetainers. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose to modify Exetainers by closing them with a silicone plug, and sealing them with a stainless steel bolt and O-ring for long-term storage. Such modified Exetainers exhibited stable concentrations of H2 and CH4 exceeding 60 days of storage at atmospheric and elevated (10 ppm) concentrations. The increase of CO was still measurable, but nine times lower than in conventional Exetainers with treated septa, and can be corrected for due to its linearity by storing a standard gas alongside the samples. The proposed modification is inexpensive, scalable and robust, and thus enables reliable storage of large numbers of low-volume gas samples from remote field locations.

scholarly journals Long-term storage and regular repeated use of diluted antisera in glass staining jars for increased sensitivity, reproducibility, and convenience of single- and two-color light microscopic immunocytochemistry.

1982 ◽  
Vol 30 (6) ◽  
pp. 504-511 ◽  
Author(s):  
M V Sofroniew ◽  
U Schrell
Keyword(s):  
Nerve Cell ◽  
Immunoperoxidase Staining ◽  
Neuropeptide Immunocytochemistry ◽  
Technical Errors ◽  
Long Term Storage ◽  
Large Numbers ◽  
Increased Sensitivity ◽  
Repeated Use ◽  
Rapid Processing

A procedure is described for the dilution and storage of antisera in glass staining jars into which whole slides are immersed for incubation during light microscopic neuropeptide immunocytochemistry. Diluted antisera, stored at 4 degrees C and continuously reused, were found to be stable for long periods of time (to date over 3 years), and consistently yielded high quality staining in both single- and two-color immunoperoxidase staining. We found this procedure to be more convenient than conventional incubation procedures, allowing the more rapid processing of large numbers of slides and reducing the loss of slides due to technical errors. The consistency and reproducibility of day to day staining were also improved. The immersion of whole slides into the antisera permitted the use of long incubation times (up to 7 days) without the sections drying out, which in many cases substantially enhanced the sensitivity of the staining obtained. A procedure for two-color immunoperoxidase staining is described using diaminobenzidine for a brown color and alpha-naphthol/pyronin for a red/purple color. We found the alpha-naphthol/pyronin reaction superior to the more commonly used 4-chlornaphthol reaction as a second color. The two-color staining was found useful not only for demonstrating nerve cell bodies stained different colors, but also for staining nerve terminals one color that are around and contacting nerve cell bodies stained another color.

scholarly journals Recovery and validation of Odin/SMR long term measurements ofmesospheric carbon monoxide

2020 ◽  
Author(s):  
Francesco Grieco ◽  
Kristell Pérot ◽  
Donal Murtagh ◽  
Patrick Eriksson ◽  
Peter Forkman ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Middle Atmosphere ◽  
Phase Lock Loop ◽  
Polar Regions ◽  
Line Broadening ◽  
Mixing Ratios ◽  
Correct Location ◽  
Relative Differences ◽  
Co Observations

Abstract. The Sub-Millimetre Radiometer (SMR) on board the Odin satellite performs limb sounding measurements of the middle atmosphere to detect molecular emission from different species. Carbon monoxide (CO) is an important tracer of atmospheric dynamics at these altitudes, due to its long photochemical lifetime and high vertical concentration gradient. In this study, we have successfully recovered over 18 years of SMR observations, providing the only dataset to date being so extended in time and stretching out to the polar regions, with regards to satellite-measured mesospheric CO. This new dataset is part of the Odin/SMR version 3.0 level 2 data. The much of the level 1 dataset – except the October 2003 to October 2004 period – was affected by a malfunctioning of the Phase-Lock Loop (PLL) in the frontend used for CO observations. Because of this technical issue, the CO line could be shifted away from its normal frequency location causing the retrieval to fail or leading to an incorrect estimation of the CO concentration. An algorithm was developed to locate the CO line and shift it to its correct location. Nevertheless, another artifact causing an underestimation of the concentration, i.e. a line broadening, stemmed from the PLL malfunctioning. This was accounted for by using a broader response function. The application of these corrections resulted in the recovery of a large amount of data that was previously being flagged as problematic and therefore not processed. A validation study has been carried out, showing how SMR CO volume mixing ratios are in general in good accordance with the other instruments considered in the study. Overall, the agreement is very good between 60 and 80 km altitude, with relative differences close to zero. A positive bias at low altitudes (50–60 km) up to +20 % and a negative bias up to −20 % at high altitudes (80–100 km) were found with respect to the compared instruments.

scholarly journals Measurement report: Long-term variations in carbon monoxide at a background station in China's Yangtze River Delta region

2020 ◽  
Author(s):  
Yijing Chen ◽  
Qianli Ma ◽  
Weili Lin ◽  
Xiaobin Xu ◽  
Jie Yao ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
River Delta ◽  
Control Measures ◽  
Mixing Ratios ◽  
Significant Downward Trend ◽  
The Yrd ◽  
Long Term Variations

Abstract. This study analyzed the long-term variations in carbon monoxide (CO) mixing ratios from January 2006 to December 2017 at the Lin'an regional atmospheric background station (LAN; 30.3° N, 119.73° E, 138 m a.s.l.) in China's Yangtze River Delta (YRD) region. The CO mixing ratios were at their highest (0.69 ± 0.08 ppm) and lowest (0.54 ± 0.06 ppm) in winter and summer, respectively. The average daily variation of CO exhibited a double-peaked pattern, with peaks in the morning and evening and a valley in the afternoon. A significant downward trend of −11.3 ppb/yr of CO was observed from 2006 to 2017 at the LAN station, which was in accordance with the negative trend of the average CO mixing ratios and total column retrieved from the satellite data (the Measurements Of Pollution In The Troposphere, MOPITT) over the YRD region during the same period. The average annual CO mixing ratio at the LAN station in 2017 was 0.51 ± 0.04 ppm, which was significantly lower than that (0.71 ± 0.12 ppm) in 2006. The decrease in CO levels was largest in autumn (−15.7 ppb/yr), followed by summer (−11.1 ppb/yr), spring (−10.8 ppb/yr), and winter (−9.7 ppb/yr). Moreover, the CO levels under relatively polluted conditions (the annually 95th percentiles) declined even more rapidly (−22.4 ppb/yr, α = 0.05, r = −0.68) from 2006 (0.91 ppm) to 2017 (0.58 ppm) and the CO levels under clean conditions (the annually 5th percentiles) were relatively stable throughout the years. The long-term decline and short-term variations in the CO mixing ratios at the LAN station were mainly attributed to the implementation of the anthropogenic pollution control measures in the YRD region and to the events like Shanghai Expo in 2020 and Hangzhou G20 in 2016. The decreased CO level may influence atmospheric chemistry over the region. The average OH reactivity of CO at the LAN station is estimated to significantly drop from 4.1 ± 0.7 s-1 in 2006 to 3.0 ± 0.3 s-1 in 2017.

scholarly journals Ozone, carbon monoxide and nitrogen oxides time series at four alpine GAW mountain stations in central Europe

2010 ◽  
Vol 10 (24) ◽  
pp. 12295-12316 ◽  
Author(s):  
S. Gilge ◽  
C. Plass-Duelmer ◽  
W. Fricke ◽  
A. Kaiser ◽  
L. Ries ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Anthropogenic Impacts ◽  
Vertical Mixing ◽  
Atmospheric Composition ◽  
Altitude Range ◽  
Calibration Laboratory ◽  
Central European ◽  
Mixing Ratios ◽  
Weekly Cycles

Abstract. Long-term, ground based in-situ observations of ozone (O3) and its precursor gases nitrogen dioxide (NO2) and carbon monoxide (CO) from the four sites Hohenpeissenberg and Zugspitze (D), Sonnblick (A) and Jungfraujoch (CH) are presented for the period 1995–2007. These Central European alpine mountain observatories cover an altitude range of roughly 1000 to 3500 m. Comparable analytical methods and common quality assurance (QA) procedures are used at all sites. For O3 and CO, calibration is linked to primary calibrations (O3) or CO standards provided by the Central Calibration Laboratory (CCL) at NOAA/ESRL. All stations have been audited by the World Calibration Centre (WCC) for CO and O3 (WCC-Empa; CH). Data from long-term measurements of NO2 and CO are only available from Hohenpeissenberg and Jungfraujoch. Both sites show slightly decreasing mixing ratios of the primarily emitted NO2 and the partly anthropogenically emitted CO between 1995 and 2007. The findings are generally consistent with shorter observation periods at Zugspitze and Sonnblick and thus are considered to represent regional changes in Central European atmospheric composition at this altitude range. Over the same period, 1995–2007, the O3 mixing ratios have slightly increased at three of the four sites independent of wind sector. Trends are often more pronounced in winter and less in summer; highest declines of NO2 and CO are observed in winter and the lowest in summer, whereas the strongest O3 increase was detected in winter and lowest or even decline in summer, respectively. Weekly cycles demonstrate anthropogenic impact at all elevations with enhanced NO2 on working days compared to weekends. Enhanced O3 values on working days indicating photochemical production from anthropogenic precursors are only observed in summer, whereas in all other seasons anti-correlation with NO2 was found due to reduced O3 values on working days. Trends are discussed with respect to anthropogenic impacts and vertical mixing. The observed trends for NO2 at the alpine mountain sites are less pronounced than trends estimated based on emission inventories.

scholarly journals Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS – measurement, calibration, and volume mixing ratio calculation methods

2008 ◽  
Vol 8 (22) ◽  
pp. 6681-6698 ◽  
Author(s):  
R. Taipale ◽  
T. M. Ruuskanen ◽  
J. Rinne ◽  
M. K. Kajos ◽  
H. Hakola ◽  
...  
Keyword(s):  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Transmission Curve ◽  
Mixing Ratio ◽  
Calculation Methods ◽  
Mixing Ratios ◽  
Ratio Calculation ◽  
Gas Standard

Abstract. Proton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). This paper gives a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. The PTR-MS instrument has to be calibrated regularly with a gas standard to ensure the accuracy needed in atmospheric VOC measurements. We introduce a novel method for determining an instrument specific relative transmission curve using information obtained from a calibration. This curve enables consistent mixing ratio calculation for VOCs not present in a calibration gas standard. Our method proved to be practical, systematic, and sensitive enough to capture changes in the transmission over time. We also propose a new approach to considering the abundance of H3O+H2O ions in mixing ratio calculation. The approach takes into account the difference in the transmission efficiencies for H3O+ and H3O+H2O ions. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March–26 April 2007, the hourly averages of the mixing ratios were 0.051–0.57 ppbv for formaldehyde, 0.19–3.1 ppbv for methanol, 0.038–0.39 ppbv for benzene, and 0.020–1.3 ppbv for monoterpenes. The detection limits for the hourly averages were 0.020, 0.060, 0.0036, and 0.0092 ppbv, respectively.

scholarly journals Recovery and validation of Odin/SMR long-term measurements of mesospheric carbon monoxide

2020 ◽  
Vol 13 (9) ◽  
pp. 5013-5031
Author(s):  
Francesco Grieco ◽  
Kristell Pérot ◽  
Donal Murtagh ◽  
Patrick Eriksson ◽  
Peter Forkman ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Middle Atmosphere ◽  
Phase Lock Loop ◽  
Polar Regions ◽  
Line Broadening ◽  
Mixing Ratios ◽  
Correct Location ◽  
Relative Differences ◽  
Co Observations

Abstract. The Sub-Millimetre Radiometer (SMR) on board the Odin satellite performs limb sounding measurements of the middle atmosphere to detect molecular emission from different species. Carbon monoxide (CO) is an important tracer of atmospheric dynamics at these altitudes, due to its long photochemical lifetime and high vertical concentration gradient. In this study, we have successfully recovered over 18 years of SMR observations, providing the only dataset to date being so extended in time and stretching out to the polar regions, with regards to satellite-measured mesospheric CO. This new dataset is part of the Odin/SMR version 3.0 level 2 data. Much of the level 1 dataset – except the October 2003 to October 2004 period – was affected by a malfunctioning of the phase-lock loop (PLL) in the front end used for CO observations. Because of this technical issue, the CO line could be shifted away from its normal frequency location, causing the retrieval to fail or leading to an incorrect estimation of the CO concentration. An algorithm was developed to locate the CO line and shift it to its correct location. Nevertheless, another artefact causing an underestimation of the concentration, i.e. a line broadening, stemmed from the PLL malfunctioning. This was accounted for by using a broader response function. The application of these corrections resulted in the recovery of a large amount of data that was previously being flagged as problematic and therefore not processed. A validation study has been carried out, showing how SMR CO volume mixing ratios are in general in good accordance with the other instruments considered in the study. Overall, the agreement is very good between 60 and 80 km altitude, with relative differences close to zero. A positive bias at low altitudes (50–60 km) up to +20 % and a negative bias up to −20 % at high altitudes (80–100 km) were found with respect to the comparison instruments.

The effect of microorganisms on the change of fat acidity value during long-term storage of wheat grain

2021 ◽  
pp. 13-15
Author(s):  
Артём Валерьевич Яицких ◽  
Людмила Витальевна Ванина ◽  
Людмила Геннадьевна Приезжева
Keyword(s):  
Storage Temperature ◽  
Linear Increase ◽  
Grain Storage ◽  
Safe Storage ◽  
Long Term Storage ◽  
Huge Impact ◽  
Food Grain ◽  
Social Environmental ◽  
New Research

Задача производства экологически чистых продуктов питания стоит в ряду важнейших мировых проблем. Она обусловлена целым рядом вопросов медицинского, социального, экологического и экономического порядка, объединенных актуальностью сохранения здоровья населения. Решение задач обеспечения сохранности продовольственного зерна пшеницы может осуществляться не только на базе действующих нормативных правил, но и с учетом результатов новых исследований. Разработана методика определения норм свежести (безопасного хранения) и годности зернопродуктов по значению кислотного числа жира (КЧЖ). Огромное влияние на зерно оказывают микроорганизмы, при этом количество плесеней хранения не нормируется для продовольственного зерна. Учитывая, что в любой зерновой массе присутствуют микроорганизмы, которые при определенных условиях развиваются по экспоненциальной кривой, авторами статьи была экспериментально установлена зависимость изменения КЧЖ от микробиологического показателя. Приведены результаты изменения биохимических, физико-химических и микробиологических показателей качества продовольственного зерна пшеницы урожаев 2015 и 2018 гг. при длительном лабораторном хранении в условиях повышенных (+30 °С), умеренных (+20 °С) и пониженных (+10 °С) температур. Установлено, что при хранении продовольственного зерна пшеницы при различных влажностно-температурных режимах в течение 24 мес происходит линейное увеличение показателя КЧЖ. Хранение зерна происходило в лабораторных условиях, определена зависимость изменения КЧЖ от температуры хранения зерна, а также неизменность показателя от развития плесеней хранения, что свидетельствует о возможности использования этого показателя для установления объективных и достоверных сроков безопасного хранения и годности. The task of producing organic food is one of the most important global problems. It is due to a number of medical, social, environmental and economic issues, united by the relevance of preserving the health of the population. The solution of the problems of ensuring the safety of food grain of wheat can be carried out not only on the basis of the current regulatory rules, but also taking into account the results of new research. A method has been developed for determining the norms of freshness (safe storage) and the suitability of grain products by the value of fat acidity value indicator (FAV). Microorganisms have a huge impact on grain, while the number of storage molds is not standardized for food grain. Considering that in any grain mass there are microorganisms that, under certain conditions, develop along an exponential curve, the authors of the article experimentally established the dependence of the change in the FAV on the microbiological indicator. The results of changes of the biochemical, physico-chemical and microbiological indicators of the quality of wheat food grain of the 2015 and 2018 harvests were given during long-term laboratory storage in conditions of increased (+30 °C), medium (+20 °C) and reduced (+10 °C) temperature. It is established that during the storage of wheat food grain under various humidity and temperature conditions a linear increase of the FAV arises within 24 months, change dependency FAV on grain storage temperature and indicator permanence on storage mold development are determined, which indicates the possibility of using this indicator to establish objective and reliable terms of safe storage and validity. Grain storage took place in laboratory conditions.

scholarly journals Competitive Growth Advantage of Nontoxigenic Mutants in the Stationary Phase in Archival Cultures of Pathogenic Vibrio cholerae Strains

2004 ◽  
Vol 72 (9) ◽  
pp. 5478-5482 ◽  
Author(s):  
Kalidas Paul ◽  
Amalendu Ghosh ◽  
Nilanjan Sengupta ◽  
Rukhsana Chowdhury
Keyword(s):  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Competitive Growth ◽  
Reading Frame ◽  
Fitness Advantage ◽  
Long Term Storage ◽  
Pathogenic Vibrio ◽  
Large Numbers ◽  
Concomitant Reduction

ABSTRACT Spontaneous nontoxigenic mutants of highly pathogenic Vibrio cholerae O1 strains accumulate in large numbers during long-term storage of the cultures in agar stabs. In these mutants, production of the transcriptional regulator ToxR was reduced due to the presence of a mutation in the ribosome-binding site immediately upstream of the toxR open reading frame. Consequently, the ToxR-dependent virulence regulon was turned off, with concomitant reduction in the expression of cholera toxin and toxin-coregulated pilus. An intriguing feature of these mutants is that they have a competitive fitness advantage when grown in competition with the parent strains in stationary-phase cocultures which is independent of RpoS, the only locus known to be primarily associated with acquisition of a growth advantage phenotype in bacteria.

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