A PARAMAGNETIC METHOD FOR MEASURING THE CARBON DIOXIDE CONCENTRATION OF A GAS

Growth of Plants in Different Oxygen Concentrations

In the past, experiments on controlled atmosphere storage have tested specific combinations of carbon dioxide and oxygen, usually in a manner which precludes determination of the effect of change in concentration of these gases. The data from the series of trials discussed in this paper permitted an investigation of the effect of concentrations of carbon dioxide and oxygen on the incidence of scald with simple and multiple linear regression techniques. The method was applied to data from three types of controlled atmosphere storage: (1) Carbon dioxide 2.5–10% at 2.5% oxygen, (2) Oxygen 1.25–20%, at near zero carbon dioxide, (3) Carbon dioxide 3.3–10.9% oxygen 2.2–16%. The relation between scald (Y), carbon dioxide concentration (x), and the reciprocal of oxygen concentration (z), was described by the regression equation: Y = y + b(x – x) + c(z – z), which implies that scald is directly proportional to carbon dioxide concentration and indirectly proportional to oxygen concentration. The effects of changes in concentration of the gases, as estimated by the regression coefficients, were consistent for size of fruit, season, and orchard, but the effect for oxygen was dependent on the method of maintaining the atmosphere. Good control of scald was obtained with low oxygen atmospheres, even after storage for 6–7 months.

The increase in carbon dioxide in the atmosphere is one of the main causes of global warming. Remote sensing technology has become an important means of monitoring the distribution of carbon dioxide gas. By remotely monitoring the temporal and spatial distributions of atmospheric carbon dioxide, people can further deepen their understanding of the global carbon process. The GOSAT (Greenhouse Gases Observing SATellite) CO2 L4B concentration data from 2010 to 2015 were validated using local station atmospheric data. The spatial and temporal distributions of the carbon dioxide concentration and its variation characteristics were analyzed. Based on the total primary productivity data and human emissions of carbon dioxide data, the influencing factors of spatial variations in carbon dioxide were analyzed. The results show that: (1) The correlation coefficient between GOSATL4B data and ground-measured data is above 0.95, which indicates that the remotely acquired data have high precision and stability. (2) The spatial distribution characteristics of carbon dioxide at different atmospheric pressure heights are quite different. The variation in the long-term series mean of carbon dioxide concentration levels at 17 vertical heights was studied. The fluctuations in concentration changes at different height levels vary, and the closer to the surface, the greater the fluctuation is. The near-surface carbon dioxide concentration (975 hPa) has the largest fluctuation. When the atmospheric pressure is low (for example, 150 or 100 hPa), the high carbon dioxide concentration region is banded and concentrated near the equator. The trends in carbon dioxide concentration over land and sea surfaces are similar, and the common pattern is that the concentration of carbon dioxide has been increasing. (3) The near-surface carbon dioxide concentration (975 hPa) has clearly different spatial characteristics. There are four high-value centers across the globe: East Asia, western Europe, the US East Coast, and Central Africa. The concentration of carbon dioxide in the Northern Hemisphere near the ground is higher than that in the Southern Hemisphere. The fluctuation in the Southern Hemisphere is relatively small, and the trend is opposite that in the Northern Hemisphere. (4) The concentration of carbon dioxide showed a significant growth trend during the study period. By studying the change characteristics of the monthly global average at the 975 hPa level (approximately 300 m above sea level) from January 2010 to October 2015, it can be seen that the global CO2 concentration has been above 400 ppm for most of the year, and it is increasing each year. (5) Compared with the Southern Hemisphere, the cyclical changes in carbon dioxide concentration in the Northern Hemisphere are obvious and large, while the trend in the Southern Hemisphere is relatively stable, and the change is small. There are opposite trends in the cyclical changes in the carbon dioxide concentration in the Northern and Southern Hemispheres. When the carbon concentration in the Northern Hemisphere resides over the annual high-value area, the Southern Hemisphere has a low-value area of carbon dioxide concentration every year. In addition, the change in carbon dioxide concentration during the year is obvious with seasonal changes. This should be related to changes in vegetation phenology and different seasons in the Northern and Southern Hemispheres. (6) Four countries in East Asia (Korea, Mongolia, Japan and China) from 2010 to 2014 were selected to analyze the relationship between GPP (gross primary production) and near-surface carbon dioxide concentration. These two factors have a significant inverse correlation. When carbon dioxide is at a minimum, the GPP is at its peak, and when carbon dioxide reaches its peak, the GPP reaches a minimum. The above relationship fully indicates that terrestrial ecosystems play an important role as carbon sink contributors in the carbon cycle. (7) The relationship between atmospheric carbon dioxide and carbon dioxide data from human activities from the Global Atmospheric Research Emissions Database was analyzed. The former is significantly and positively correlated with carbon dioxide emissions caused by human activities, indicating that human activities are an important factor in the increase in carbon dioxide.

Fresh pork chops packaged in air, vacuum, and eleven modified gas atmospheres and stored at 4°C were studied to determine the influence of varying the concentrations of carbon dioxide and oxygen on the microbiological, physical and chemical characteristics of the chops. The concentrations of carbon dioxide and oxygen were in the range of 0 to 40%. The headspace gaseous composition changed over time as the concentration of the carbon dioxide increased while that of the oxygen decreased during storage. Increasing the carbon dioxide concentration delayed growth of aerobic psychrotrophic and mesophilic bacteria, and the Enterobacteriaceae, but slightly enhanced that of lactic acid bacteria. Increasing the oxygen concentration reduced growth of facultative anaerobic and anaerobic bacteria and enhanced that of Brochotrix thermosphacta. In general, carbon dioxide had more influence on the microbiological storage life of the chops than oxygen. Increasing the carbon dioxide concentration also reduced the redness of the chops, increased purge losses and promoted lipid oxidation, but retarded the formation of volatile basic nitrogen (VBN). Increasing oxygen concentration also increased lipid oxidation but generally there was no interactive effect of carbon dioxide and oxygen for all the parameters tested. Modified gas atmospheres with more than 10% carbon dioxide concentration were superior to air for extending the microbiological storage life of fresh pork chops. Gas mixture containing 20%C02 without oxygen was as effective as mixtures containing 40%C02 with or without oxygen in extending the storage life of fresh pork chops. Mixtures containing 40%C02 with or without oxygen had better performance than

ASSIMILATION AND RESPIRATION OF EXCISED LEAVES AT HIGH CONCENTRATIONS OF CARBON DIOXIDE

Unpublished results obtained by J. K. Hardy (1939) indicate that, under conditions in which carbon dioxide was allowed to accumulate in the atmosphere as a result of the activity of apples when enclosed in gas-tight containers in the absence of oxygen, there was no evidence, over a short period, of a fall in the rate of carbon dioxide production with increasing concentrations of carbon dioxide in the atmosphere, and hence in the tissues. Previous results (Kidd & West, I937) had shown that in air the rate of carbon dioxide production of apples during their post-climacteric phase is progressively depressed with rising concentration of carbon dioxide in the atmosphere, and hence in the tissues. If aerobic carbon dioxide production is depressed by the presence of carbon dioxide but anaerobic carbon dioxide production is not depressed, the fact must be of interest in connexion with the intermediate theories of metabolism of the respiratory process. Experiments have been conducted to check Hardy's results by a method in which the fruits were exposed to a relatively constant pressure of carbon dioxide over a longer period. The method used for the estimation of carbon dioxide production by apples in the presence of carbon dioxide i-n air has already been described (Kidd & West, I933). The experiments were carried out at io0C. Three samples of Bramley's Seedling apples were obtained on 29 September I939. In the case of two of these samples (nos. i and 2) the fruit was pre-climacteric, and in the other (no. 3) post-climacteric. The respiratory history of these three samples is shown in Fig. i (top). The first sample (no. i) was exposed, at the outset, to an atmosphere of pure nitrogen, and it can be seen, by comparing the results with those of the second sample (no. 2), which was in air, that transference from air to nitrogen had very little effect on the rate of carbon dioxide production. Both these samples were preclimacteric. At the point marked A the sample in nitrogen was transferred to an atmosphere of 100% carbon dioxide in nitrogen from which all traces of oxygen had been removed. The carbon dioxide caused a slight, though definite, depression in respiratory activity. At B when the sample was returned to nitrogen without carbon dioxide, oxygen still being absent, the respiratory activity rose again slightly. The second sample (no. 2), which was in air at the outset, began to show its climacteric rise after about 7 days. On the ioth day, before the climacteric rise had fully developed, it was transferred to nitrogen at the point C. The respiratory activity in nitrogen remained on the pre-climacteric level. At the point D when it was transferred to i o % carbon

This experiment was conducted to observe the effect of the composition of atmospheric gases on the respiration of fruits and vegetables. The average of repiration rate of eggplants, Japanese pears, spinach and cauliflower (under storage in modified atmosphere) were lower than that under storage in air. Especially, the respiration rate of the products stored in modified atmosphere conta fined 5% oxygen and 5% carbon dioxide was about half of that in air. (Experiment I.)It is clear that a decline in the respiration of these products in storge is brought about by a combination of super-normal carbon dioxide concentration and reduced oxygen concentration. However, the data in experiment I has not been elucidated which is the main fatter concerning the reduction in respiration.In order to test the precise contribution of each of these fatter, experiment II was conducted both tests on oxygen and carbon dioxide concentrations in atmospheric gases on the respiration of vegetables. Carbon dioxide test was carried out at the range of 0-20% and oxygen test was carried out at the range of 5-25%.In this experiment, the respiration rate of some vegetables could be controlled either by decrease of oxygen concentration or by increase of carbon dioxide concentration.It was found that there was three phases to control the respiration rate in practical CA-storage. Three phases were as follows: (1) decrease of oxygen concentration, (2) increase of carbon dioxide concentration and (3) both decrease of oxygen concentration and increase of carbon dioxide concentration. Vegetables showed pattern (1) were spinach, pea in pod, kidney bean, lettuce, bell peppers and eggplants. They were very sensitive to the oxygen content in atmospheric gases. Cauliflower belonged to pattern (2) which shows relatively sensitive carbon dioxide concentration. Other vegetables which are pattern (3) are strawberries, celery, tomatoes, welsh onion and garden asparagus. These vegetables were sensetive to carbon dioxide and oxygen concentration in the atmospheric gases. Thus, it was considered that the response of vegetables to special gases reducing the respiration was different from the kinds of vegetables.

Characteristics of the large-scale circulation during episodes with high and low concentrations of carbon dioxide and air pollutants at an arctic monitoring site in winter

The behaviour of Jonathan apples in storage was studied in relation to the concentrations of carbon dioxide and oxygen in the storage atmosphere. A factorial design of 2, 4, and 6 per cent carbon dioxide and 1.2, 2.2, and 13.2 per cent oxygen was used and apples were removed from storage at 32�F after 20, 23, and 26 weeks. The concentrations of carbon dioxide and oxygen in the storage atmosphere were related quantitatively to weight loss, ground colour, firmness, titratable acidity, and to the incidence of superficial scald and breakdown. Rest retention of weight, acids, ground colour, and firmness, and least wastage from superficial scald were found in atmospheres with high carbon dioxide and low oxygen concentrations, but more of the fruit in these atmospheres had breakdown.

Experimental determination of hydrate phase equilibrium for different gas mixtures containing methane, carbon dioxide and nitrogen with motor current measurements

Diffusivity is a strong function of concentration and an important transport property. Diffusion of multiple species is far more frequent than the diffusion of one species. However, there are limited experimental data available on multi-component diffusivity. The objective of this study is to develop an optimal control framework to determine multi-component concentration-dependent diffusivities of two gases in a non-volatile phase such as polymer. In Part 1 of this study, we derived a detailed mass-transfer model of the experimental diffusion process for the non-volatile phase to provide the temporal masses of gases in the polymer. The determination of diffusivities is an inverse problem involving principles of optimal control. Necessary conditions are determined to solve this problem. In Part 2 of this study, we utilized the results of Part 1 to determine the concentration-dependent, multi-component diffusivities of nitrogen and carbon dioxide in polystyrene. To that end, solubility and diffusion experiments are conducted to obtain necessary data. In the ternary system of nitrogen (1), carbon dioxide (2), and polystyrene (3), the diffusivities and D11, D12, D21, and D22 versus the gas mass fractions are two-dimensional surfaces. The diffusivity of carbon dioxide was found to be greater than that of nitrogen. The value of the main diffusion coefficient D11 was found to increase as the concentration of carbon dioxide increased. The highest value of D11 obtained was 2.2 X 10^-8m^2s^-1 for nitrogen mass fraction of 3.14 X10^-4 and for a carbon dioxide mass fraction of 5.67 X 10^-4 . The cross-diffusion coefficient increased as the concentrations of nitrogen and carbon dioxide increased. The diffusivity reached its maximum value when the concentrations of nitrogen and carbon dioxide were at their maximum values. The diffusivity was of the order of 10^-9m^2s^-1. The diffusivity of the cross-diffusion coefficient D21 was found to be increased for the mass The diffusivity of the cross-diffusion coefficient was found to be increased for the mass fractions of carbon dioxide ranging from 0 to 1.70 X 10^-3 . The diffusivity was found to be of the order of . The diffusion coefficient, D22, was found to increase with the concentrations of nitrogen and carbon dioxide, D22 remained high with low concentrations of carbon dioxide. The diffusivity was found to be of the order of 10^-7m^2s^-1

Diffusivity is a strong function of concentration and an important transport property. Diffusion of multiple species is far more frequent than the diffusion of one species. However, there are limited experimental data available on multi-component diffusivity. The objective of this study is to develop an optimal control framework to determine multi-component concentration-dependent diffusivities of two gases in a non-volatile phase such as polymer. In Part 1 of this study, we derived a detailed mass-transfer model of the experimental diffusion process for the non-volatile phase to provide the temporal masses of gases in the polymer. The determination of diffusivities is an inverse problem involving principles of optimal control. Necessary conditions are determined to solve this problem. In Part 2 of this study, we utilized the results of Part 1 to determine the concentration-dependent, multi-component diffusivities of nitrogen and carbon dioxide in polystyrene. To that end, solubility and diffusion experiments are conducted to obtain necessary data. In the ternary system of nitrogen (1), carbon dioxide (2), and polystyrene (3), the diffusivities and D11, D12, D21, and D22 versus the gas mass fractions are two-dimensional surfaces. The diffusivity of carbon dioxide was found to be greater than that of nitrogen. The value of the main diffusion coefficient D11 was found to increase as the concentration of carbon dioxide increased. The highest value of D11 obtained was 2.2 X 10^-8m^2s^-1 for nitrogen mass fraction of 3.14 X10^-4 and for a carbon dioxide mass fraction of 5.67 X 10^-4 . The cross-diffusion coefficient increased as the concentrations of nitrogen and carbon dioxide increased. The diffusivity reached its maximum value when the concentrations of nitrogen and carbon dioxide were at their maximum values. The diffusivity was of the order of 10^-9m^2s^-1. The diffusivity of the cross-diffusion coefficient D21 was found to be increased for the mass The diffusivity of the cross-diffusion coefficient was found to be increased for the mass fractions of carbon dioxide ranging from 0 to 1.70 X 10^-3 . The diffusivity was found to be of the order of . The diffusion coefficient, D22, was found to increase with the concentrations of nitrogen and carbon dioxide, D22 remained high with low concentrations of carbon dioxide. The diffusivity was found to be of the order of 10^-7m^2s^-1

This supplementary comparison is designed to test the capabilities of the participants to measure and certify carbon dioxide in nitrogen, and to provide supporting evidence for the CMCs of institutes for carbon dioxide. Indeed this comparison aims to demonstrate the capabilities of IPQ in the production of primary gas mixtures of carbon dioxide in nitrogen and for the participant laboratories to demonstrate their capabilities on certifying primary gas mixtures of percent levels of carbon dioxide in nitrogen.Moreover, a number of NMIs had already participated in the key comparison CCQM-K52, but in a lower range. This EURAMET comparison offers an opportunity to the laboratories to submit CMC in a higher range.In this comparison the laboratories analysed the gas mixtures that are gravimetrically produced and analyzed by IPQ. Each cylinder had its own reference value calculated from the gravimetric preparation. The pressure in the cylinders was approximately 10 MPa; aluminum cylinders of 5 dm3 nominal volume were used.This comparison provides evidence in support of CMCs for carbon dioxide within the range of 1.0 × 10−2 mol/mol to 20.0 × 10−2 mol/mol in a nitrogen/air balance.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The objectives of this book are threefold: (1) discussion of the role of photosynthesis in regulating atmopsheric concentrtions of carbon dioxide and oxygen; (2) promotion of research and discussion about how the various carbons and CAM carbon cycles and algal carbon dioxide concentrating mechanisms could be integrated to help explain the regulation of atmospheric carbon dioxide; (3) increase of exchanges among biochemists concerned primarily with detailed reactions of photsynthetic carbon dioxide metabolism, and geologists and other concerned about increasing atmospheric carbon dioxide. Sections include those on background information on global carbon cycles and pools; the C3 cycle, photorespiration, and respiration, and the carbon dioxide concentration processes of C4 CAM and Algal pumps; discussion of plant metabolism might influence atmospheric carbon dioxide and oxygen concentrations.

Measurement of carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) concentration in modified atmosphere packaging (MAP) food is critical to be carried out by the food industry. A slight variation in concentrations of CO2, O2, and N2 in food packaging may have a significant impact on product quality and safety for human health. Accurate and reliable measurement of CO2, O2, and N2 concentrations in food packaging is crucial, and it can only be achieved by calibrating the gas analyzer. This study aimed to develop gas mixtures for the calibration of CO2, O2, and N2 gas analyzers at a typical concentration range of modified atmosphere packaging. The calibration gas mixtures were prepared gravimetrically by following ISO 6142. The concentration ranges of CO2, O2, and N2 for calibration gas mixtures were set at 9-19% mol/mol, 1-5% mol/mol, and 74-88% mol/mol, respectively. Each parent gas was identified for its impurities using gas chromatography with a pulsed discharge helium ionization detector (GC-PDHID). The compositions of CO2, O2, and N2 in the mixtures were verified by evaluating the internal consistency within the prepared gas mixtures using gas chromatography with a thermal conductivity detector (GC-TCD). The short term stability of the prepared gas mixtures was evaluated using an equal division method. The result showed that good internal consistency was achieved between the gravimetrical and GC’s verification values, having linear regression coefficient (R2) ≥ 0.999. The t-test result has shown that CO2 has better short term stability than O2 and N2. In conclusion, the developed calibration gas mixtures at a typical concentration range of modified atmosphere packaging have shown satisfying results for CO2 component. However, further evaluation is still required to minimize the instability of O2 and N2 components.