Enzyme electrode for the determination of salicylate

Measurement of carbon monoxide in simulated expired breath

Electrodes for blood pO2 and pCO2 determination.

Molecular modeling in design of polyaniline for polymer-based carbon dioxide sensor

Modified Atmosphere Packaged (MAP) food employs a protective gas mixture, which normally contains selected amounts of carbon dioxide (CO₂) and oxygen (O₂), in order to extend the shelf life of food. Conventional MAP analysis of package integrity involves destructive sampling of packages followed by carbon dioxide and oxygen detection. For quality control reasons, as well as to enhance food safety, the concept of optical on-pack sensors for monitoring the gas composition of the MAP package at different stages of the distribution process is very attractive. The objective of this work was to develop printable formulations of oxygen and carbon dioxide sensors for use in food packaging. Oxygen sensing is achieved by detecting the degree of quenching of a fluorescent ruthenium complex entrapped in a sol-gel matrix. In particular, a measurement technique based on the quenching of the fluorescence decay time, phase fluorometric detection, is employed. A scheme for detecting CO2 has been developed which is compatible with the oxygen detection scheme. It is fluorescence-based and uses the pH-sensitive 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) indicator dye encapsulated in an organically modified silica (ORMOSIL) glass matrix. Dual Luminophore Referencing (DLR) has been employed as an internal referencing scheme, which provides many of the advantages of lifetime-based fluorometric methods. Oxygen cross-sensitivity was minimised by encapsulating the reference luminophore in dense sol-gel microspheres. The sensor performance compared well with standard methods for both oxygen and carbon dioxide detection. The results of preliminary on-pack print trials are presented and a preliminary design of an integrated dual gas optical read-out device is discussed.

SummaryHomeostatic control of body fluid CO2 is essential in animals but is poorly understood. C. elegans relies on diffusion for gas exchange and avoids environments with elevated CO2. We show that C. elegans temperature, O2, and salt-sensing neurons are also CO2 sensors mediating CO2 avoidance. AFD thermosensors respond to increasing CO2 by a fall and then rise in Ca2+ and show a Ca2+ spike when CO2 decreases. BAG O2 sensors and ASE salt sensors are both activated by CO2 and remain tonically active while high CO2 persists. CO2-evoked Ca2+ responses in AFD and BAG neurons require cGMP-gated ion channels. Atypical soluble guanylate cyclases mediating O2 responses also contribute to BAG CO2 responses. AFD and BAG neurons together stimulate turning when CO2 rises and inhibit turning when CO2 falls. Our results show that C. elegans senses CO2 using functionally diverse sensory neurons acting homeostatically to minimize exposure to elevated CO2.

Development of carbon dioxide (CO 2) sensor for grain quality monitoring

A passive-chipless LC carbon dioxide sensor with non-contact ZnO/CuO/RGO nanocomposites at room temperature

Purpose There is an increase in greenhouse gasses and global climate change is frequently reported on. What can be done? Certainly to try and reduce the carbon footprint, which is not a new topic, by encouraging applications and activities for concrete during its lifetime (Portland Cement Association, 2019). This study aims to focus on introducing CO2 to normal and fly ash concrete and thus investigating the effect on the carbon footprint of the samples and the effectiveness of the CO2 introduction methods, namely, carbonated water addition during the mixing process and by means of an infusion pipe directly into the concrete when the samples are casted and have been casted. Design/methodology/approach The feasibility of carbon dioxide storage within concrete is determined by investigating the effects of introduced carbon dioxide into concrete samples and the effectiveness of the concrete at storing carbon dioxide. The concrete was mixed in a 1:3:3 ratio for the OPC or blended 52.5 R cement:sand:stone (22 mm) with a 28 day strength of 50 MPa. Samples were also prepared containing low-grade fly ash cement contents ranging from 15% to 60%. CO2 was introduced to the concrete via carbonated mixing water and an infusion pipe system directly to the hardening concrete cubes. In total, 16 g CO2 bicycle carbon dioxide inflators and valve system were used to infuse the concrete over a period of a week until the canister was emptied with valve release on the lowest setting. A compression test was carried out to determine the strength of the concrete cubes with, and without, the introduction of carbon dioxide. Results were also obtained using a scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDS) to determine how the carbon dioxide changed the microscopic composition and chemical composition of the concrete. A microcontroller with carbon dioxide sensors was used to gather carbon dioxide emission data for a period of three months. Findings The compressive strength tests show by introducing carbon dioxide to the concrete, the compressive strength has increased by as much as 13.86% as expected from the literature. Furthermore, by infusing carbon dioxide with the fly ash blended cement, will give a higher strength compared to the control with ordinary portland cement. This correlates to an overall reduction in cost for the structure. The optimal fly ash content for the control with minimal strength degradation is 30%. Where the optimal fly ash content for the concrete with carbon dioxide stored within, is 45%. The SEM analysis showed the concrete with sequestered carbon dioxide has significantly more calcium silicate hydrate (C-S-H) gel formation, thus the strength increase. Furthermore, the carbon dioxide emission test showed the concrete with infused carbon dioxide stores carbon dioxide more efficiently compared to the control sample. With the data showing the infused sample releases 11.19% less carbon dioxide compared to the control sample. However, the carbonated water sample releases 20.9% more carbon dioxide when compared to the control sample. Thus the introduction of carbon dioxide by means of infusion is more effective. Practical implications This is a practical pilot investigation of carbon dioxide introduction via two methods, one being infusion of CO2 into normal concrete and fly ash concrete and two, mixing normal and fly ash concrete with carbonated water. These results show, cheaper cement can be used to achieve equivalent or better strength. This can help in the reduction of the construction industry’s carbon footprint. Originality/value By reducing the construction industry’s carbon footprint with this research results, a saving can not only be made financially in the construction industry, but this will help to preserve our environment for future generations.

Application of microbiological sensors in fermentation processes

To facilitate the effective assessment of respiratory entropy during poultry breeding, a novel oxygen (O2) and carbon dioxide (CO2) sensor was developed based on the off-axis integrated cavity output spectroscopy technique, featuring effective absorption optical paths of 15.5 m and 8.5 m, respectively. The sensor employs integrated environmental control technology, substantially enhancing detection precision. To improve the instrument's response speed, the miniaturization of the cavity and structural optimization were implemented, achieving a rapid response time of merely 6.22 s, addressing the stringent requirements for quick responsiveness in poultry respiration thermometry research. A signal processing model tailored for on-site applications was designed, boosting the system's signal-to-noise ratio by 4.7 times under complex environmental noise conditions. Utilizing Allan variance analysis, the sensor's detection limits for O2 and CO2 were ascertained to be 2.9 ppm and 7.4 ppb, respectively. A 24-h field application test conducted in Gongzhuling demonstrated that the sensor's results align with the respiratory characteristics of poultry under normal physiological conditions, validating its extensive potential for application in respiratory analysis, environmental monitoring, and industrial sectors.

Aim: This detailed research involves in improving the performance accuracy of forest fire detection in comparison between evergreen forest zone and temperate forest zone by sensing temperature and atmospheric carbon dioxide level. Materials and Method: In this analysis, Group 1 consists of temperature values (n = 16) and atmospheric carbon dioxide concentration levels (n = 16) in an evergreen forest zone. Group 2 consists of temperature values (n = 16) and atmospheric carbon dioxide concentration level (n = 16) after incidence of fire. This novel Fire detection method, the G-power analysis was done on the samples with maximum power of 0.8 for the system with an error correction of 0.5. Results: The proposed novel forest fire detection has a better accuracy in evergreen forest (93.3 %) in comparison with temperate forest (90.8 %). The significance value is observed to be 0.198 using temperature sensors and 0.219 using carbon dioxide sensors. Conclusion: The novel forest fire detection system using temperature and carbon dioxide sensors, appears to have better accuracy of 93.3 % to locate the existence of forest fire in evergreen forest.

The mechanism of the CH4/O2 reaction on the Pd–Pt/γ-Al2O3 catalyst: A SSITKA study

Carbon dioxide is a colourless and odourless gas and detection of carbon dioxide is critical to maintaining the quality of breathable air in the atmosphere. The current concentration of carbon dioxide in the atmosphere is 400 ppm and this concentration has increased manifold in the past 50 years or so leading to global warming and other climate phenomena. Exposure to 2000 – 5000 ppm of carbon dioxide causes poor concentration, increased heart rate and nausea and when the concentration is > 5000 ppm, oxygen deficiency may occur. This creates an urgent need to develop sensors suitable to carbon dioxide detection. Semiconducting metal oxides such as SnO2 (n-type), CuO (p-type), ZnO (n-type) WO3 (n-type) etc. have long been considered for detecting reducing gases such as carbon monoxide, hydrogen and methane. However, such metal oxides perform poorly when it comes to carbon dioxide detection. Thus, we have proposed the formation of p-n junctions with n-type metal oxide (ZnO) and p-type perovskite (LaFe0.8Co0.2O3) that has been shown previously to aid carbon dioxide sensing. LaFe0.8Co0.2O3 (LFCO) – ZnO composite thin films have been synthesized using wet chemical synthesis in which the mol % of LFCO has been varied. The role of both homo and heterojunctions in carbon dioxide sensing can be elucidated from this configuration. This configuration is cross-sensitive to carbon monoxide and mathematical analyses has been performed to differentiate it from carbon dioxide. LFCO – ZnO thin films with a single p-n junction has also been synthesized and it has been found that this configuration is much more selective to carbon dioxide than the previous one. In addition to this, the role of LFCO – ZnO multi-layered thin films has also been explored with respect to carbon dioxide sensing.

After completing this article, readers should be able to: 1. Define the indeterminate class of recommendations for neonatal resuscitation. 2. Describe the two areas of current investigation within the indeterminate class recommendations. 3. Describe the application of two techniques from other settings within the indeterminate class recommendations. 4. Describe the indeterminate class recommendation for which conflicting evidence is emerging. With the shift to evidence-based guidelines, the process of revising the scientific framework for neonatal resuscitation and the derivative educational efforts will become more predictable and accessible. Beginning with the International Guidelines 2000, an Indeterminate Class of recommendations appeared. These focused on areas of intense scientific research that may lead to clinically important therapies; technological developments widely adopted for use in other age groups that may find a role in neonatal resuscitation; or emerging evidence that conflicts substantially with previous data, resulting in a revision of recommendations to withdraw support of a particular therapeutic approach. The advent of changes in evidence-based guidelines carries the obligation to monitor the impact of such changes. Finally, entirely new questions and proposed guideline recommendations will be submitted to evidence evaluation in the future. Five Indeterminate Class recommendations appeared in the neonatal resuscitation portion of the International Guidelines 2000 (Table⇓ ). Cerebral hypothermia following hypoxic-ischemic insult and positive-pressure ventilation with room air represent proposals in the translational research phase, moving from animal and molecular models into clinical trials. The recommendations relating to adjunctive airway techniques, laryngeal mask airway and exhaled carbon dioxide detection, recognize the importance of these techniques in the older pediatric and adult populations, but acknowledge the significant limitations in their application to neonates. The statement regarding high-dose epinephrine reinforces the conflicting nature of evidence relating to this therapy, yet it acknowledges that available evidence is extrapolated largely from older age groups and falls short of supporting …

This paper presents an experimental study on anode reactions in direct ethanol fuel cells with the effect of cell operating conditions on the generation ratio of anode reaction products (i.e. carbon dioxide, acetic acid, and methane). Decreasing the ethanol concentration in the fuel increased the generation ratio of carbon dioxide. Additionally, lowering the fuel flow rate produced more carbon dioxide. Thus, we conducted a detailed experiment using acetaldehyde which is an intermediate product of the anode reaction of ethanol. Similar to using ethanol as a fuel, more carbon dioxide was produced at a lower fuel concentration and at a slower flow rate. Additionally, increasing the oxygen concentration in the cathode gas significantly increased the carbon dioxide generation ratio, which was likely because the oxygen from the cathode side reaches at the anode via the electrolyte membrane to promote the carbon dioxide production reaction. The amount of carbon dioxide produced greatly exceeded the amount of oxygen permeated, and comparing the amount of generated current with the amounts of acetic acid and carbon dioxide suggests that another oxide is present at the anode. The methane generation ratio was not affected by the oxygen concentration. It is assumed that the decreasing fuel concentration at the electrode surface due to a lower fuel flow rate increases the carbon dioxide generation ratio. Isotope analysis on the generated carbon dioxide confirmed that the detected carbon dioxide was due solely to the oxidation of fuel and not due to the oxidation of electrode materials such as the catalyst support.