A Mixed-Gas Control System for an Environmental Chamber

For the design of high oxygen modified atmosphere packages, knowledge and modelling of respiration rates at both low and super‐atmospheric oxygen levels is required. Fresh‐cut butterhead lettuce was stored in glass jars at three different temperatures (1 °C, 5 °C and 9 °C), three carbon dioxide levels (0, 10 and 20 kPa) and eight different levels of oxygen partial pressures (0, 2, 5, 10, 20, 50, 70 and 100 kPa). Oxygen consumption and carbon dioxide production rates were measured. The respiration rates were significantly reduced by low temperatures and elevated carbon dioxide concentrations up to 10 kPa. At carbon dioxide concentrations of 20 kPa the respiration rates were comparable to those at 0 kPa CO2 probably due to an injury response. Oxygen concentrations had to be below 2 kPa to significantly reduce the respiration rates compared to air conditions. Respiration rates were also slightly lower under super‐atmospheric (50, 70 and 100 kPa) oxygen partial pressures than at air conditions. Additionally, a Michaelis–Menten based model to describe the respiration rates as a function of oxygen, carbon dioxide and temperature was constructed. Models that include respiration rates at super‐atmospheric oxygen levels have not previously been described. The inhibitive effects of carbon dioxide and high oxygen concentrations were incorporated by an uncompetitive and a non‐competitive inhibition term respectively. Temperature effects were described using Arrhenius' law. The model gave a good description (R2adj = 0.82) of the oxygen consumption and carbon dioxide production rates over the temperature, oxygen and carbon dioxide range tested. Copyright © 2006 Society of Chemical Industry

Mild intermittent hypoxia protocols are characterized by a few (e.g. 12 episodes) brief episodes (e.g. 2 min) of mild hypoxia (e.g. 85–87 % oxygen saturation) interspersed with short recovery periods (Mateika & Sandhu 2011; Puri et al., 2021). In animal models, exposure to this stimulus leads to the initiation of long-term facilitation (LTF), which is a term used to characterize sustained increases in motor neuron, nerve or muscle activity initiated in animals following exposure to mild intermittent hypoxia. The sustained increases in motoneuronal activity have been linked to downstream increases in ventilation, upper airway patency and limb muscle function in animal models (Mateika et al., 2015). Some of the neuronal pathways and cellular mechanisms responsible for the sustained increase in activity have been determined (Mitchell & Baker 2022). Many studies completed over the past two decades have attempted to initiate LTF of ventilation, upper airway muscle or limb muscle activity in humans (Mateika & Sandhu 2011; Puri et al., 2021). However, the initiation of this phenomenon, or the magnitude of the phenomenon when it manifests, has been variable when comparisons are made across studies (see supplements in Mateika & Sandhu 2011; Puri et al., 2021). Potential reasons for this variability include differences in the number and duration of episodes that formulate mild intermittent hypoxia protocols, along with differences in the intensity of hypoxia considered to fall within the mild range (Mateika & Sandhu 2011; Puri et al., 2021). Likewise, some protocols have employed a combination of intermittent hypoxia and hypercapnia (see section below on 'Potential Mechanisms that Link Carbon Dioxide to the Initiation and Manifestation of LTF' for further discussion of this point) rather than intermittent hypoxia alone. Moreover, different human models (i.e. healthy humans, humans living with obstructive sleep apnoea (OSA), humans living with spinal cord injury) have been used to explore this phenomenon (Mateika & Sandhu 2011; Puri et al., 2021). These experimental design variations could be responsible for the variability that has been reported. On the other hand, we propose that one of the primary keys to the initiation and subsequent manifestation of LTF in humans is the presence of sustained levels of carbon dioxide during and following exposure to mild intermittent hypoxia. We and others established two decades ago that ventilatory LTF (vLTF) (Harris et al., 2006; Jordan et al., 2002; Khodadadeh et al., 2006; Mateika et al., 2004) and LTF of upper airway muscle activity (Harris et al., 2006) does not manifest in healthy humans (Harris et al., 2006; Jordan et al., 2002; Mateika et al., 2004) or humans with sleep apnoea (Khodadadeh et al., 2006) following exposure to mild intermittent hypoxia, when carbon dioxide levels are uncontrolled and hypocapnia ensues. Subsequent to these findings, ongoing studies provided additional insight by showing that sustained increases in respiratory and limb muscle function in humans, often presented in the framework of spinal cord injury, are frequently not evident following exposure to mild intermittent hypoxia in the presence of uncontrolled carbon dioxide levels (Gandevia & Butler 2024). Given the inaugural findings, these latter results are not surprising because common neural pathways and cellular mechanisms have been proposed to be involved in the initiation of LTF of respiratory and limb motor neurons based on work completed in animal models. To confirm the important role that carbon dioxide has in the initiation of LTF in humans, we took two approaches. The first approach was to show that even though vLTF was not evident during recovery from mild intermittent hypoxia in the presence of uncontrolled carbon dioxide, this phenomenon became evident in the presence of progressively increasing carbon dioxide levels (Khodadadeh et al., 2006; Mateika et al., 2004). Specifically, participants completed rebreathing studies before and following exposure to mild intermittent hypoxia that was unaccompanied by the manifestation of LTF (Khodadadeh et al., 2006; Mateika et al., 2004). During the rebreathing tests, hypoxia was sustained at 50 mmHg and carbon dioxide slowly increased over time. We showed that the ventilatory response to hypoxia at carbon dioxide levels 3 and 6 Torr above the recruitment threshold was elevated during the rebreathing tests completed after compared to before exposure to intermittent hypoxia (Khodadadeh et al., 2006; Mateika et al., 2004). This difference was not evident at carbon dioxide levels that demarcated the recruitment threshold (i.e. 0 Torr above the recruitment threshold) (Khodadadeh et al., 2006; Mateika et al., 2004). We suggested that this increased ventilatory response was due to the initiation of LTF. In subsequent experiments, we demonstrated that LTF of ventilation and genioglossus muscle activity was clearly evident when carbon dioxide levels were sustained above baseline (i.e. 5 mmHg above baseline in this study) throughout and following exposure to mild intermittent hypoxia, but was not evident if we reduced carbon dioxide levels back to baseline levels (Harris et al., 2006). Once this finding was established, we showed that exposure to acute mild intermittent hypoxia in the presence of sustained hypercapnia ( MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ ) resulted in vLTF in healthy men and women (Wadhwa et al., 2008) and that the magnitude of the response was independent of sex. We also showed that vLTF was initiated in individuals with OSA (Gerst et al., 2011; Syed et al., 2013) and that the magnitude of the response was greater compared to healthy individuals (Syed et al., 2013). Likewise, exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ lead to the initiation of LTF in individuals with spinal cord injury (Tester et al., 2014). Moreover, we initiated vLTF during wakefulness and sleep in humans (Syed et al., 2013) and showed that the magnitude of the response was greater during wakefulness. We also showed that repeated daily exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ enhanced the magnitude of LTF in humans (Gerst et al., 2011) and was greater in the evening compared to the morning in individuals with obstructive sleep apnoea (Gerst et al., 2011). In the studies completed over the years, the degree to which carbon dioxide was sustained above baseline ranged from 2–5 mmHg (Panza et al., 2023). In all cases, vLTF was evident, although the magnitude of the response varied (Panza et al., 2023) (see section below on 'Potential Mechanisms that Link Carbon Dioxide to the Initiation and Manifestation of LTF' for further discussion of this point). The mechanistic role(s) that sustained elevated levels of carbon dioxide have in the initiation and manifestation of LTF following exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ is not fully established, although there are a number of possibilities. Spinal motoneurons associated with movement and breathing are innervated in part by similar medullary neuronal pathways (e.g. raphe neurons) that are activated by peripheral chemoreflexes that respond to mild intermittent hypoxia. Thus, the inability to initiate LTF in spinal motoneurons could be a result of peripheral chemoreflex feedback that is insufficient to activate downstream mechanisms. Our recent findings support this suggestion (Panza et al., 2023). We showed in humans (n = 124) that the magnitude of LTF is predicted in part by the sensitivity of the hypoxic ventilatory response, which reflects peripheral chemoreflex sensitivity (Panza et al., 2023). It is well established that increasing the level of sustained carbon dioxide for a given level of hypoxia is associated with an increase in the hypoxic ventilatory response (Duffin & Mateika 2013). Given this relationship, the input from the peripheral chemoreceptors known to initiate LTF will be severely diminished in the presence of hypocapnia. Thus, maintaining carbon dioxide levels in the presence of mild intermittent hypoxia serves to ensure that an adequate stimulus originating from the peripheral chemoreceptors exists to initiate LTF. It is also possible that LTF is initiated but does not manifest because uncontrolled carbon dioxide is reduced significantly below a well-defined threshold (referred to as the apnoeic threshold during sleep and the recruitment threshold during wakefulness) leading to the cessation of breathing. The cessation of breathing via reductions in carbon dioxide is easily induced during sleep using artificial ventilation and is evident in some individuals during wakefulness following hyperventilation. Consequently, if carbon dioxide is significantly reduced during the application of mild intermittent hypoxia and the reduction in carbon dioxide endures after exposure, LTF might not be evident in measures of ventilation because of the withdrawal of this powerful stimulus, even though the phenomenon was initiated (Mateika & Narwani 2009). This possibility is particularly applicable to spinal motoneurons that innervate respiratory muscles and receive inputs from medullary respiratory neurons and other neuronal groups (i.e. raphe neurons) that have a role in initiating LTF. Thus, maintaining levels of carbon dioxide may impact both the initiation and manifestation of LTF. Lastly, sustained elevated levels of carbon dioxide, independent of mild intermittent hypoxia, could activate distinct neuronal and cellular pathways that independently initiate LTF (Mateika et al., 2018). Work completed using animal models has indicated that separate neuronal pathways that offset each other are activated by intermittent hypoxia and intermittent hypercapnia (Kinkead et al., 2001). On the other hand, to our knowledge, pathways activated by sustained levels of carbon dioxide in the context of initiating LTF have not been discovered (Mateika et al., 2018). Nonetheless, studies in humans have revealed that sustained levels of hypercapnia can lead to ventilatory drift which suggests that novel mechanisms may be activated by this stimulus (Harris et al., 2006). However, there is also evidence to suggest that sustained hypercapnia is not solely responsible for the magnitude of LTF. We have shown that the magnitude of the drift in ventilation recorded in response to sustained hypercapnia is much smaller than the response recorded when humans are exposed to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ (Gerst et al., 2011). Thus, it is possible that MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ initiates LTF via the interaction of separate mechanistic pathways (Mateika et al., 2018). If so, allowing carbon dioxide levels to decrease in an uncontrolled manner would result in the removal of a stimulus that is capable of initiating LTF independently. Given that sustained levels of carbon dioxide appears to have an important role in initiating vLTF in healthy humans (Harris et al., 2006; Wadhwa et al., 2008) and humans living with sleep apnoea (Syed et al., 2013) or spinal cord injury (Tester et al., 2014), MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ may ultimately prove to be an effective therapeutic modality that has a multipronged effect on numerous physiological systems including respiratory and cardiovascular outcomes in individuals living with sleep apnoea (Puri et al., 2021). We have begun to explore this possibility and, to date, our work has focused on outcome measures linked to upper airway patency and cardiovascular function. We showed that acute and repeated daily exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ improves upper airway patency (El-Chami et al., 2017; Panza et al., 2022). Reduced critical closing pressure measures indicated that upper airway patency improves following exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ (Panza et al., 2022). In addition, we showed that continuous positive airway pressure (CPAP) required to treat sleep apnoea was reduced as a consequence of improved upper airway patency and as a result treatment adherence improved (Panza et al., 2022). Presently, we are exploring whether exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ also dampens responses to tactile pressure and auditory noise, which are stimuli often experienced when patients are treated with CPAP. If our preliminary findings are correct, these additional modifications might increase the arousal threshold to these stimuli, which could contribute to improving treatment adherence. Given the changes in the critical closing pressure that indicate improvement in upper airway patency we expected that acute exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ would be coupled to decreases in the apnoea/hypopnea index (Syed et al., 2013). This was not the case and we postulated that other forms of plasticity (i.e. progressive augmentation) initiated by MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ may override any benefits associated with improved airway patency in the absence of CPAP treatment (Mateika & Narwani 2009). We are presently exploring whether timing of exposure and length of exposure might alter the balance between these forms of plasticity and their impact on apnoea severity. Improvement in treatment adherence could have important implications for modifying cardiovascular outcome measures in individuals with sleep apnoea. Moreover, MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ might have direct effects on cardiovascular outcomes independent of improved adherence. To date, we have shown that repeated daily exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ results in a significant decrease in blood pressure in OSA patients treated nightly with CPAP (Panza et al., 2022). We are following up these studies by exploring whether this decrease is evident in the OSA population independent of nightly treatment with CPAP. Likewise, we are exploring whether blood pressure modifications are sustained for long periods of time. Our preliminary data suggests that this is the case because reductions in blood pressure following treatment with MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ are sustained for up to 8 weeks in most individuals. There are a number of additional studies to be performed in the coming years. The mechanisms underlying the impact of MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ on select outcomes measures are of interest, particularly in the context of teasing out the roles of MIH and sustained carbon dioxide individually and combined. It is also of interest to explore whether sustaining elevated carbon dioxide levels is necessary to attain maximum therapeutic value for all outcome measures or whether this requirement is limited to specific physiologic responses. In addition, studies designed to determine the efficacy of different doses of MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ , at the same time as considering the concurrent impact of hypoxic sensitivity on efficacy, comprise an important next step. In the context of these dosing studies, the potential safety issues related to exposure to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ should be further explored. It is possible that some subgroups within a given population (e.g. low vs. high hypoxic sensitivity) will not benefit from this therapy or will experience detrimental outcomes, which could be an additional explanation for the variable responses that have been reported to date. However, it should be noted that in our studies and other published studies significant adverse events linked to MI H C O 2 ${\mathrm{MI}}{{{\mathrm{H}}}_{{\mathrm{C}}{{{\mathrm{O}}}_2}}}$ have not been reported. Likewise, based on prior work the timing of administration of this stimulus and its effectiveness on outcome measures, particularly as it relates to improvement in the severity of OSA, will be an important contribution to the existing literature. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. No competing interests declared. J.H.M. was responsible for the conception of the work. J.H.M., R.B. and D.M.K. contributed to drafting the work or revising it critically for important intellectual content. J.H.M., R.B. and D.M.K. approved the final version of the manuscript submitted for publication and agree to be accountable for all aspects of the work by ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Lastly, all persons designated as authors qualify for authorship, and all those who qualify for authorship are listed. This work was supported by the United States Department of Veterans Affairs (I01CX00125, IK6CX002287) and the National Institute of Heart, Lung and Blood (R01HL085537).

Objectives The purpose of this study is to examine changes in carbon dioxide concentration and noise levels in classrooms, and to analyze the effects of these changes on elementary school students' attention and problem behaviors. Methods First, To measure the change of carbon dioxide and noise levels in classrooms, theses levels were measured in general classroom, specific subject classroom, and specific subject classroom with ventilation system operating. Second, to analyze the effect of carbon dioxide and noise levels on students’ attention and problem behavior, situations where both carbon dioxide and noise levels are low (cLnL), only carbon dioxide levels are high (cHnL), and only noise levels are high (cLnH), and both carbon dioxide and noise levels are high (cHnH). Results The carbon dioxide concentration in each classroom ranged from 400 to 1951.8 ppm, and the noise level ranged from 12.6 to 96.6 db(A). As a result of analyzing the effects of carbon dioxide and noise levels on attention and problem behavior, it was resulted that the higher the noise level, the negatively correlated with Work instruction comprehension, Selective attention, and Sustained attention. In addition, problem behaviors occurred the least (3 times) in the cLnL group and the most (31 times) in the cHnH group. Conclusions Carbon dioxide concentration and noise levels in the school exceeded the standard. The learning environment can affect not only students' attention and problem behavior, but also their health. To improve this, physical environment improvement is required.

Carbon assimilation at low carbon dioxide levels was measured on three Oryza specics (O. sativa L. cv. Toyonishiki, O. officinalis Wall, and O. meyriana Baill.), Brassica napus L. cv. Michinokunatane and Triticum aestivum L. cv. Konosu No.25. Measurements were made at two different oxygen concentrations; 140% and 21% (atmospheric pressure). An improvement in measurement device was made for ensuring an accuracy of the meter readings. That is, a recorder with a modulator was used to enlarge the differences in the carbon dioxide concentration; two- and five-fold for carbon dioxide levels above and below carbon dioxidc compensation point (gamma), respectively. It seems that HEATH and ORCHARD (1968) and HOLMGREN and JARVIS (1967) Changed the carbon dioxide concentration at large intervals, resulting in 3 to 5 measurements below gamma. Such a few measurements would obscure the statistics of the carbon dioxide exchangc rate at low carbon dioxide levels. The changes of carbon dioxide concentration in this experiment, however, were made at intervals of about 2 or 4 ppm from 0 ppm to gamma, resulting in 7 to 14 mean values below it. As the characteristics of carbon dioxide absorption at low carbon dioxide levels, GABRIELSEN (1948) proposed the 'threshold hyPothesis' in which gamma was regarded as a threshold value below which no assimilaton occurred, while HEATH and 0RCHARD (1968) postulated the existence of a 'third process', in addition to ordinary (dark) respiration and assimilation, which could be expected to have a different balance between respiration and assimilation. They denied the adoptation of the threshold hypothesis. From the prescnt experiment in which the carbon dioxide exchange rates were traced by Changing the Carbon dioxide concentrations at very small intervals, hwever, it appeared that the rate of carbon dioxide uptake at low carbon dioxide levels and atmospheric oxygen pressure tended to decrease toward 1/2 gamma carbon dioxide level, and the carbon dioxide uptake seems to cease and only the carbon dioxide release secms to occur below it. In case of measurements at 14% oxygen concentration the situation was similar to those at 2l% oxygen concentration, but a considerable decrease of the value of gamma. Thus, the process of carbon dioxide uptake at low carbon dioxide levels seems to imply the threshold hypothesis and 1/2 gamma seems to be an approximation of the threshold value. The assimilation rate is estimated as the ratio of carbon dioxide concentration differences between ambient air and assimilation center to the sum of diffusion resistances.As an estimate of carbon dioxide levels in the assimilation center in this formula, GAASTRA (1959) proposed zero, while BIERHUIZEN and SLAYTER (1964) adopted the Practise of using gamma to estimate it. From the results mentioned above, we could propose to use 1/2 gamma as its primary approximation because the photosynthetic center would be exposed to this carbon dioxide level but not absorb it.

In their annual indoor air quality assessment for ADNOC Schools, the Abu Dhabi Education Council has reported hazardous levels (∼3000 ppm) of carbon dioxide in fifteen classrooms. Exposure of 5,090 students attending the school for ∼eight hours (typical school day) to such high levels of carbon dioxide would induce adverse health conditions like headaches, drowsiness, and lack of concentration on the short term and serious diseases like asthma and sick building syndrome on the long term. The Health, Safety, and Environment committee of the school has identified clogged air intake vents and dirty AC filters as the main cause of the high carbon dioxide concentrations reported. The outdoor (ambient) carbon dioxide level is measured and has an eight-hour average value of 419 ppm. After cleaning thoroughly, the indoor levels of carbon dioxide, temperature, and relative humidity were monitored simultaneously in each classroom and have average values of ∼1117 ppm, ∼24°C, and ∼37%, respectively. In addition, the average indoor-to-outdoor ratio of carbon dioxide has been improved from 3000 / 419 ≈ 7.2 before cleaning the AC filters to an average ratio of ( 1,117 / 419 ≈ 2.7 ) after cleaning. Thus, ventilation rates in the classrooms monitored in this project are adequate and the corrective actions taken were effective.

Evidence-based nursing practice is essential to the delivery of high-quality care that optimizes patients' outcomes. Studies continue to show improved outcomes when best evidence is used in the delivery of patient care. Despite awareness of the importance of practicing by using best evidence, achieving and sustaining evidence-based practice within practice environments can be challenging, and research suggests that integration of evidence-based practice into daily clinical practice remains inconsistent. This article addresses 4 practice issues that, first, are within the realm of nursing and if changed might improve care of patients and, second, are areas in which the tradition and the evidence do not agree and practice continues to follow tradition. The topics addressed are (1) noninvasive measurement of blood pressure in children, (2) oxygen administration for patients with chronic obstructive pulmonary disease, (3) intravenous catheter size and blood administration, and (4) infection control practices to prevent infections. The related beliefs, current evidence, and recommendations for practice related to each topic are described.

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.

This article was developed based on the results of an instrumental study of microclimate parameters such as: temperature, air humidity, and CO2 carbon dioxide concentration in bomb shelters and shelters. The results of the article were obtained within the framework of the project 101082898 — UKRENERGY “Innovative Master Courses Supporting the Improvement of the Energy and Carbon Footprint of the Ukrainian Building Stock” EDU-2022-CBHE-STRAND-2) envisages the creation of new master's programs on the topic “Energy efficiency, modernization of buildings and energy planning” in Ukrainian universities and the promotion of best practices of the EU regarding educational methodologies and specific knowledge related to energy efficiency and sustainability of buildings, in particular, the introduction of innovative master's courses on energy efficiency and reducing the carbon footprint in the building stock of Ukraine [1]. This article shows the graphical dependence of the main parameters of the microclimate, such as temperature, air humidity, and the concentration of CO2 carbon dioxide, on various modes of operation of the building. Instrumental monitoring of the microclimate parameters of the bomb shelter and shelter was carried out using the NT-2000 logger. During 5 hours, parameters of temperature, relative humidity and level of carbon dioxide were monitored in different modes of operation, i.e. depending on the number of people in the room and depending on the mode of opening the external doors. During the study, the NT-2000 logger was located in the bomb shelter and shelter at a height of 1,2 m from the floor [2]. At both facilities, when a large number of people were in the research room, a significant increase in the CO2 index was recorded. When people left the research room, the logger continued to record the values of temperature, air humidity and CO2 concentration for two hours. During this period, not a single person was in the room, CO2 and temperature decreased steadily. the level of carbon dioxide in the bomb shelter dropped from 1 100 ppm to 550 ppm in 120 minutes. In the shelter, it dropped from 1 385 ppm to 819 ppm in 120 minutes. During the same period, the temperature in both cases decreased, in the bomb shelter from 10 to 8 oC, in the shelter from 14 to 11 oC. According to these indicators, a graph of the dependence of the parameters of temperature, relative humidity and carbon dioxide level depending on different modes of operation was constructed. The graph shows two values of CO2 at the beginning and at the end of the period of decrease in CO2 concentration over a period of 120 minutes. We can calculate the area of ​​the figure formed by two points of the ΔСО2 concentration values ​​as a function of the difference in the values ​​of the ΔСО2 indicators during the time interval t. Based on the obtained value of the area of ​​the figure, it is possible to give a relative qualitative assessment of the infiltration rate of the building [3]. In this way, a simplified instrumental method of qualitative assessment of the infiltration parameter was obtained. The next step is to obtain not only a qualitative but also a quantitative assessment of the infiltration parameter using an instrumental method of determining CO2 concentration, temperature and air humidity.

Physiologic effects and measurement of carbon dioxide and oxygen levels during qualitative respirator fit testing

Journal Article Carbon Dioxide as a Control Agent for the Rusty Grain Beetle (Coleoptera: Cucujidae) in Stored Wheat Get access N. D. G. White, N. D. G. White Agriculture Canada Research Station, Winnipeg, Manitoba R3T 2M9 Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar D. S. Jayas, D. S. Jayas Agriculture Canada Research Station, Winnipeg, Manitoba R3T 2M9 Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar R. N. Sinha R. N. Sinha Agriculture Canada Research Station, Winnipeg, Manitoba R3T 2M9 Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Economic Entomology, Volume 83, Issue 1, 1 February 1990, Pages 277–288, https://doi.org/10.1093/jee/83.1.277 Published: 01 February 1990 Article history Received: 21 February 1989 Accepted: 18 May 1989 Published: 01 February 1990

The final swimming speed of juvenile largemouth bass, Micropterus salmoides (Lacépède), was reduced markedly at oxygen concentrations below 5 or 6 mg/liter in tests at 25 C in a tubular chamber in which the velocity of water was increased gradually, at 10-min intervals, until the fish were forced by the current permanently against a screen. At levels above 6 mg/liter, the final swimming speed was virtually independent of the oxygen concentration. The performance of bass that had been acclimated overnight to elevated carbon dioxide levels was not materially affected by the highest tested concentrations of free carbon dioxide, averaging 48 mg/liter, at any tested level of dissolved oxygen.For juvenile coho salmon, Oncorhynchus kisutch (Walbaum), at temperatures near 20 C and carbon dioxide concentrations near 2 mg/liter, any considerable reduction of the oxygen concentration from about 9 mg/liter, the air-saturation level, resulted in some reduction of the final swimming speed. The performance of the salmon was impaired much more markedly than was that of the bass by the same reduction of the oxygen concentration. At oxygen concentrations near and above the air-saturation level, high concentrations of free carbon dioxide averaging 18 and 61 mg/liter had a depressing effect on the final swimming speed of coho salmon even after overnight acclimation. However, this effect decreased at reduced oxygen concentrations. No measurable effect of free carbon dioxide concentrations near 61 mg/liter was evident at 2 mg/liter dissolved oxygen, and concentrations near 18 mg/liter had little or no effect even at moderately reduced dissolved oxygen levels after overnight acclimation of the salmon to these carbon dioxide concentrations.

Lactic acid, carbon dioxide and human sweat stimuli were presented singly and in combination to femaleAedes aegypti(Linnaeus) within a wind-tunnel system. The take-off, flight, landing and probing responses of the mosquitoes were recorded using direct observation and video techniques. The analyses determined the nature of the response to different stimuli and the concentration ranges within which specific behaviours occurred. A threshold carbon dioxide concentration for taking-off of approximately 0.03% above ambient was detected. Lactic acid and human sweat samples did not elicit take-off when presented alone, however, when they were combined with elevated carbon dioxide, take-off rate was enhanced in most of the combinations tested. Flight activity was positively correlated with carbon dioxide level and some evidence for synergism with lactic acid was found within a narrow window of blend concentrations. The factors eliciting landing were more subtle. There was a positive correlation between landing rate and carbon dioxide concentration. At the lowest carbon dioxide concentration tested, landing occurred only in the presence of lactic acid. Within a window of low to intermediate concentrations, landing rate was enhanced by this combination. At the highest carbon dioxide concentration, landing was however inhibited by the presence of lactic acid. The sweat extract elicited landings in the absence of elevated carbon dioxide. This indicated the presence of chemical stimuli, other than lactic acid, active in the short range. Probing occurred only at low carbon dioxide concentrations and there was no probing when lactic acid alone was tested. There was however probing in the presence of combined stimuli, the level of response seemed to be positively correlated with the ratio of carbon dioxide and lactic acid concentrations.

Impact of increased flow rate on specific growth rate of juvenile turbot ( Scophthalmus maximus, Rafinesque 1810)

Predictive modelling and validation of Listeria innocua growth at superatmospheric oxygen and carbon dioxide concentrations

This study was conducted to develop and evaluate an appropriate control device for a purge type controlled atmosphere (CA) storage in Korea. To determine ideal performance, oxygen and carbon dioxide control capability and airtightness were analyzed according to the postharvest management manual of CA storage of Fuji apples. In shortened experiments for CA storage, the condition was delayed CA at 0-0.5°C for three days and stored at 0.1-0.5% carbon dioxide levels for 3 days and then further stored 6 days under 1% carbon dioxide. As a result, the temperature control range of a developed CA container was 0.0-0.5°C, and the relative humidity was more than 90%, except for the defrosting step for the freezer during the storage period. The rate of pressure reduction for the CA container in the negative and positive pressure states was 0.45 and 0.21 mmH2O/min, respectively, and it was twofolds higher than standard airtightness for CA storage. After nitrogen injection, oxygen concentration was achieved at 2%, and carbon dioxide concentration was maintained at 0.1-0.5% for 6 days. Afterwards, carbon dioxide levels were tightly controlled between 0.1-1.0%. These results suggest that a developed purge type CA container could be effective in commercially maintaining the quality of agricultural products.