Fluorescent Carbon Dioxide Indicators

There are few analytes in the world as significant as carbon dioxide, the basic chemical feedstock of life. Through green plant photosynthesis, carbon dioxide is converted to the fuel and food necessary for the continued existence of most known forms of life. In addition carbon dioxide is an indicator of the existence of life and a measure of health via respiration. Not surprisingly, therefore, one of the key, basic analytes routinely monitored in the blood of hospital patients is the level of dissolved carbon dioxide. The measurement of carbon dioxide levels is also an important feature of environmental monitoring, providing, as it does, an important indicator of the health of the hydrosphere or atmosphere. The use, presence and measurement of carbon dioxide are also important in many industries, including brewing and the biotechnologies. In the food industry, a revolution in food packaging has come about through the use of carbon dioxide in modified atmosphere packaging (MAP). In many industries, the use, or presence, of carbon dioxide is commonplace and its measurement and continuous monitoring essential. In this article, the basic concepts behind the major, different colourimetric and luminescent optical sensors for the detection and quantitative analysis of carbon dioxide are reviewed and illustrated with examples. The major applications of these sensors are discussed and their strengths and weaknesses highlighted.

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.

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.

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.

Viruses are nonliving biological entities whose host range encompasses all known forms of life. They are deceptively simple in description (a protein shell surrounding genetic material with an occasional lipid envelope) and yet can infect all known forms of life. Recently, due to technological advancements, viruses from more extreme environments can be studied through both culture-dependent and independent means. Viruses with thermophilic, halophilic, psychrophilic, and barophilic properties are highlighted in this paper with an emphasis on the properties that allow them to exist in said environments. Unfortunately, much of this field is extremely novel and thus, not much is yet known about these viruses or the microbes they infect when compared to non-extremophilic host–virus systems. With this review, we hope to shed some light on these relatively new studies and highlight their intrinsic value.

The objective of the present study was to investigate whether analysis of carbon dioxide, acetone and/or butanol present in human breath can be used as a simple and noninvasive diagnosis method for obstructive sleep apnea syndrome (OSAS). For this purpose, overnight changes in the concentrations of these breath molecules were measured before and after sleep in 10 patients who underwent polysomnography and were diagnosed with OSAS, and were compared with the levels of these biomarkers determined after sleep in 10 healthy subjects. The concentrations of exhaled carbon dioxide were measured using external cavity laser-based off-axis cavity enhanced absorption spectroscopy, whereas the levels of exhaled acetone and butanol were determined using thermal desorption gas chromatography mass spectrometry. We observed no significant changes in the levels of exhaled acetone and carbon dioxide in OSAS patients after sleep compared with pre-sleep values and compared with those in healthy control subjects. However, for the first time, to our knowledge, analyses of expired air showed an increased concentration of butanol after sleep compared with that before sleep and compared with that in healthy subjects. These results suggest that butanol can be established as a potential biomarker to enable the convenient and noninvasive diagnosis of OSAS in the future.

Grass attack

Four species, Sinapis alba L., Medicago sativa L., Gypsophila paniculata L. and Picea abies (L.) Karsten, were grown in three light regimes: darkness, low light (25 μmol m −2 s −1 for 10 min d −1 ) and high light (120 μmol m −2 s −1 for 12 h d −1 ) and four levels of carbon dioxide: 0, 350, 700 and 1400±50 μl l −1 . Germination was not affected by any of the treatments. The effects of carbon dioxide on stem elongation were identical in low and high light: stem length increased at a decreasing rate with level of carbon dioxide in all species. Level of carbon dioxide also affected stem elongation in complete darkness, but the pattern was more complex and varied among species. Total weight did not vary with level of carbon dioxide to any significant extent in either darkness or low light, but increased with level of carbon dioxide at high light in all four species. Due to the absence of any effect of carbon dioxide on growth in darkness and low light, we suggest the effects of carbon dioxide on stem elongation are independent of effects on growth and may be due to a direct interaction with developmental processes. In contrast, level of carbon dioxide had little effect on allocation patterns in the dark and low light experiments, but had marked effects in high light. Therefore, the effect of carbon dioxide on allocation was probably due to the effects of carbon dioxide on growth rather than to any direct interaction between carbon dioxide and development. An understanding of the mechanisms by which carbon dioxide affects development may help us understand the often variable effects of carbon dioxide upon plants.

Assessing the growth-stimulating effect of tea waste compost in urban agriculture while identifying the benefits of household waste carbon dioxide

Rusty grain beetle, Cryptolestes ferrugineus (Stephens), populations in bins (58 cm diameter, 168 cm high) holding 322-kg bulks of wheat were controlled in 4-6 wk at 25 ± 3°C when carbon dioxide (CO2) levels were about 20% and oxygen (O2) levels were between 5 and 10%. At temperatures declining from 21 to 7°C, 99.6% of C. ferrugineus populations were killed in 12 wk when carbon dioxide levels gradually fell from 20 to 9% and oxygen levels rose from 16 to 19.5%. Gas levels, temperature, grain moisture content, C. ferrugineus adult and larval numbers, seed germination, and seed infection by Aspergillus glaucus group and Penicillium spp. fungi were monitored for 12 wk in two experiments at either 25°C or <21°C. In the first experiment at 25°C, unsealed control bins; sealed storage bins; and sealed treatment bins with 20, 30, and 45% CO2, respectively, were used. Temperature.(higher at the top of the grain mass), carbon dioxide (lower at the top), oxygen, moisture (higher at the top), germination (lower at the top), and numbers of C. ferrugineus adults (lower at the top) and larvae (higher at the top, except at 30 and 45% CO2) were significantly different at different levels throughout the 163-cm columns of wheat. In the second experiment at 21 to 7°C, carbon dioxide and oxygen levels were similar throughout the columns of grain in unsealed control and sealed bins. In 10 and 20% CO2 treatments, carbon dioxide levels were 2-3% higher in bottom than top samples. All variables except moisture were significantly different at different storage times in both experiments. All variables except Penicillium infection and moisture content in the warm grain or seed germination in the cool grain were different among treatments.

Global warming occurs when air pollutants collect in the atmosphere and absorb sunlight and solar radiation, and as much as 80% of global warming is caused by carbon dioxide alone. Many metropolitan cities like Delhi, India have carbon dioxide (CO2) levels 11 times higher than the levels recommended by the World Health Organization. Prior research has mainly concentrated on removing CO2 from sources like automobile exhaust and industry effluents. However, there has been limited research pertaining to the use of hydroxides to reduce CO2 in ambient air. We therefore conducted experiments to identify the most suitable hydroxide in solid form to capture low concentrations of CO2. Furthermore, we explored the possibility of using an electrically-charged drone to reduce CO2 in the air using a solid hydroxide. Our results indicate that sodium hydroxide (NaOH) is most suitable for scrubbing CO2 from air, with up to 90% reduction in carbon dioxide levels under the experimental conditions. Since the troposphere stretches up to 13 km above sea level and military drones can fly up to 18 km above sea level, drone attachments with CO2-absorbing chemicals could potentially clean the air at all levels in the troposphere. Our study provides a possible solution to mitigate the harmful impacts of carbon dioxide present in the atmosphere.

We assessed the central-chemoreflex ventilatory responses to carbon dioxide in six male volunteers using a hyperoxic rebreathing technique. Hyperventilation prior to rebreathing allowed both the threshold and the sensitivity of the response to be measured. We used immersion in water to control the body temperature (tympanic). The water temperature was adjusted to be either thermo-neutral or hot so that body temperature either remained normal [+0.2 (0.04) degrees C, mean (SEM)] or was elevated by 1.5 (0.08) degrees C. The sensitivities of the central-chemoreflex ventilatory responses to carbon dioxide were increased at elevated body temperatures, changing from a mean of 1.8 (0.2) 1.min-1. Torr-1 to 2.7 (0.1) 1.min-1. Torr-1. However, the thresholds did not change with temperature, and the mean threshold was 48(1) Torr at both normal and elevated temperatures. For all of the volunteers, ventilation was increased at elevated body temperatures for all levels of carbon dioxide, mainly by changes in respiratory frequency due to reductions in expiratory times. At subthreshold levels of carbon dioxide, mean ventilation changed significantly from 6.3(1.1) 1.min-1 at normal temperatures to 10.8 (1.9) 1.min-1 at elevated temperatures. Heart rates also increased significantly with temperature, changing from a mean of 66 (4) beats.min-1 to 102 (3) beats.min-1 at threshold levels of carbon dioxide. The mean rates of rise of carbon dioxide partial pressure during rebreathing were significantly increased with temperature as well, changing from 0.075 (0.008) Torr.min-1 to 0.089 (0.004) Torr.min-1. We concluded that elevating the body temperatures of our subjects not only increased their ventilation, heart rates and metabolic rates at all levels of carbon dioxide, but it also increased the sensitivity of their central chemoreflex ventilatory responses to carbon dioxide. Despite these increases, the thresholds of the central-chemoreflex ventilatory responses to carbon dioxide remained unchanged.

Carbon dioxide level as a migraine threshold factor: Hypothesis and possible solutions

Abnormal levels of end-tidal carbon dioxide (EtCO2) during resuscitation in the delivery suite are associated with intraventricular haemorrhage (IVH) development. Our aim was to determine whether carbon dioxide (CO2) levels in the first 3 days after birth reflected abnormal EtCO2 levels in the delivery suite, and hence, a prolonged rather than an early insult resulted in IVH. In addition, we determined if greater EtCO2level fluctuations during resuscitation occurred in infants who developed IVH. EtCO2 levels during delivery suite resuscitation and CO2 levels on the neonatal unit were evaluated in 58 infants (median gestational age 27.3 weeks). Delta EtCO2 was the difference between the highest and lowest level of EtCO2. Thirteen infants developed a grade 3–4 IVH (severe group). There were no significant differences in CO2 levels between those who did and did not develop an IVH (or severe IVH) on the NICU. The delta EtCO2 during resuscitation differed between infants with any IVH (6.2 (5.4–7.5) kPa) or no IVH (3.8 (2.7–4.3) kPA) (p < 0.001) after adjusting for differences in gestational age. Delta EtCO2 levels gave an area under the ROC curve of 0.940 for prediction of IVH.Conclusion: The results emphasize the importance of monitoring EtCO2 levels in the delivery suite.What is Known:• Abnormal levels of carbon dioxide (CO2) in the first few days after birth and abnormal end-tidal CO2levels (EtCO2) levels during resuscitation are associated in preterm infants with the risk of developing intraventricular haemorrhage (IVH).What is New:• There were no significant differences in NICU CO2levels between those who developed an IVH or no IVH.• There was a poor correlation between delivery suite ETCO2levels and NICU CO2levels.• Large fluctuations in EtCO2during resuscitation in the delivery suite were highly predictive of IVH development in preterm infants.