Low Concentrations Of Carbon Monoxide Research Articles

Experimental investigation of steam and carbon dioxide influence on methane filtration combustion in a reversal flow porous media reactor

A reverse flow porous medium reactor with premixed and non-premixed flames was experimentally investigated to evaluate the influence of steam and carbon dioxide on methane (CH4) filtration combustion for syngas production. Premixed, non-premixed, and non-premixed with steam were the tested cases for different injection configurations. Thermal profiles, combustion products, hydrogen (H2) and carbon monoxide (CO) yields for several equivalence ratios are analyzed. Non-premixed case exposed higher maximum temperatures due to the reactant accumulation at the crosswise injection position, with a temperature of 1615 K. The lack of homogenization of the reactants in this configuration leads to low H2 and high CO concentrations compared to the premixed case. The maximum CO yield was 92.81% for the non-premixed configuration with alternated air injection, while the maximum H2 yield was 37.8% for the premixed air-methane-steam case. It was found that the air-methane-carbon dioxide mixtures had lower temperatures, combustion wave velocities, and H2 and CO concentrations, compared to the air-methane, and air-methane-steam mixtures, but higher CH4 and CO2 concentrations. The premixed configuration with air-methane-carbon dioxide mixture showed higher temperatures, and H2 and CO concentrations, compared to the non-premixed configuration. Further studies are necessary to optimize the operation of these types of reactors.

Association between risk of preterm birth and long-term and short-term exposure to ambient carbon monoxide during pregnancy in chongqing, China: a study from 2016-2020

BackgroundPreterm birth (PTB) is an important predictor of perinatal morbidity and mortality. Previous researches have reported a correlation between air pollution and an increased risk of preterm birth. However, the specific relationship between short-term and long-term exposure to carbon monoxide (CO) and preterm birth remains less explored.MethodsA population-based study was conducted among 515,498 pregnant women in Chongqing, China, to assess short-term and long-term effects of CO on preterm and very preterm births. Generalized additive models (GAM) were applied to evaluate short-term effects, and exposure-response correlation curves were plotted after adjusting for confounding factors. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using COX proportional hazard models to estimate the long-term effect.ResultsThe daily incidence of preterm and very preterm birth was 5.99% and 0.41%, respectively. A positive association between a 100 µg/m³ increase in CO and PTB was observed at lag 0–3 days and 12–21 days, with a maximum relative risk (RR) of 1.021(95%CI: 1.001–1.043). The exposure-response curves (lag 0 day) revealed a rapid increase in PTB due to CO. Regarding long-term exposure, positive associations were found between a 100 µg/m3 CO increase for each trimester(Model 2 for trimester 1: HR = 1.054, 95%CI: 1.048–1.060; Model 2 for trimester 2: HR = 1.066, 95%CI: 1.060–1.073; Model 2 for trimester 3: HR = 1.007, 95%CI: 1.001–1.013; Model 2 for entire pregnancy: HR = 1.080, 95%CI: 1.073–1.088) and higher HRs of very preterm birth. Multiplicative interactions between air pollution and CO on the risk of preterm and very preterm birth were detected (P- interaction<0.05).ConclusionsOur findings suggest that short-term exposure to low levels of CO may have protective effects against preterm birth, while long-term exposure to low concentrations of CO may reduce the risk of both preterm and very preterm birth. Moreover, our study indicated that very preterm birth is more susceptible to the influence of long-term exposure to CO during pregnancy, with acute CO exposure exhibiting a greater impact on preterm birth. It is imperative for pregnant women to minimize exposure to ambient air pollutants.

Beneficial Effects of Oral Carbon Monoxide on Doxorubicin-Induced Cardiotoxicity.

Doxorubicin and other anthracyclines are crucial cancer treatment drugs. However, they are associated with significant cardiotoxicity, severely affecting patient care and limiting dosage and usage. Previous studies have shown that low carbon monoxide (CO) concentrations protect against doxorubicin toxicity. However, traditional methods of CO delivery pose complex challenges for daily administration, such as dosing and toxicity. To address these challenges, we developed a novel oral liquid drug product containing CO (HBI-002) that can be easily self-administered by patients with cancer undergoing doxorubicin treatment, resulting in CO being delivered through the upper gastrointestinal tract. HBI-002 was tested in a murine model of doxorubicin cardiotoxicity in the presence and absence of lung or breast cancer. The mice received HBI-002 twice daily before doxorubicin administration and experienced increased carboxyhemoglobin levels from a baseline of ≈1% to 7%. Heart tissue from mice treated with HBI-002 had a 6.3-fold increase in CO concentrations and higher expression of the cytoprotective enzyme heme oxygenase-1 compared with placebo control. In both acute and chronic doxorubicin toxicity scenarios, HBI-002 protected the heart from cardiotoxic effects, including limiting tissue damage and cardiac dysfunction and improving survival. In addition, HBI-002 did not compromise the efficacy of doxorubicin in reducing tumor volume, but rather enhanced the sensitivity of breast 4T1 cancer cells to doxorubicin while simultaneously protecting cardiac function. These findings strongly support using HBI-002 as a cardioprotective agent that maintains the therapeutic benefits of doxorubicin cancer treatment while mitigating cardiac damage.

Isolation and identification of carbon monoxide producing microorganisms from compost

Carbon monoxide (CO) formation has been observed during composting of various fractions of organic waste. It was reported that this production can be biotic, associated with the activity of microorganisms. However, there are no sources considering the microbial communities producing CO production in compost. This preliminary research aimed to isolate and identify microorganisms potentially responsible for the CO production in compost collected from two areas of the biowaste pile: with low (118 ppm) and high CO concentration (785 ppm). Study proved that all isolates were bacterial strains with the majority of rod-shaped Gram-positive bacteria. Both places can be inhabited by the same bacterial strains, e.g. Bacillus licheniformis and Paenibacillus lactis. The most common were Bacillus (B. licheniformis, B. haynesii, B. paralicheniformis, and B. thermolactis). After incubation of isolates in sealed bioreactors for 4 days, the highest CO levels in the headspace were recorded for B. paralicheniformis (>1000 ppm), B. licheniformis (>800 ppm), and G. thermodenitrificans (∼600 ppm). High CO concentrations were accompanied by low O2 (<6%) and high CO2 levels (>8%). It is recommended to analyze the expression of the gene encoding CODH to confirm or exclude the ability of the identified strains to convert CO2 to CO.

Influence of varying carbon oxides concentrations on the selectivity of an electrical sensor utilizing graphene nanoribbons

We have considered a graphene nano ribbon-based two probe-device working on the principle of alteration of current-voltage (I–V) characteristic, upon interactions of its channel material with the adsorbed gas molecules. The analysis of sensing parameters alongside the electron transport mechanism was carried out by using density functional theory (DFT) formulated on the Hohenberg-Kohen paradigm in conjunction with the non-equilibrium green functions (NEGF) method. Electronic transport through similar work reported earlier reveals that the combination of these two techniques coordinates extremely well and yields convincing electronic results. The nanoribbon-based sensing device was employed to evaluate its capability to detect Carbon dioxide (CO2) and Carbon monoxide (CO) molecules. Analysis of the computed result reveals significant modifications in the electronic property of the device upon adsorption of carbon dioxide and carbon monoxide entities on the channel surface. One such significant and dramatic change in the characteristic that we observed is the nature of the channel that transforms from metallic to semi-metallic. Another observed change is the signal amplification capability relative to the pristine device. The signal gets amplified on increasing number of molecular entities from one to six.The transformation in sensor performance is additionally supported by examining variations in multiple parameters, including adsorption energy, charge transfer, differential resistance, and the figure of merit, also known as the peak-to-valley ratio (PVR). The investigation unveiled that the currently designed zigzag graphene nanoribbon (ZGNR) model exhibits high sensitivity to both CO2 and CO gases. This phenomenon is substantiated by the elevated adsorption energy, increased charge transfer, elevated peak-to-valley ratio (PVR), and heightened sensor response. The substantial sensor response, registering at a magnitude of 8.3, underscores the efficacy of the current system in detecting both low and high concentrations of CO and CO2 molecules. The current study emphasizes the notion that understanding the electronic and transport behaviour of zigzag graphene nanoribbons (ZGNR) and analogous materials could offer valuable insights for addressing the threat of environmental pollution.

Exogenous carbon monoxide promotes GPX4-dependent ferroptosis through ROS/GSK3β axis in non-small cell lung cancer

The gas therapy is drawing increasing attention in the treatment of many diseases including cancer. As one of gas signaling molecules, carbon monoxide (CO) has been proved to exert anti-cancer effects via triggering multiple cell death types, such as autophagy, apoptosis and necrosis. Here, we showed that low concentration CO delivered from CO-releasing molecule 3 (CORM-3) effectively induced ferroptosis, known as a novel proinflammatory programmed cell death, in vitro and in vivo. Mechanistically, we found that CO triggered ferroptosis by modulating the ROS/GSK3β/GPX4 signaling pathway, resulting in the accumulation of lipid hydroperoxides and the occurrence of ferroptosis. We think our findings provide novel insights into the anti-cancer mechanisms of CO, and suggest that CO could potentially be exploited as a novel ferroptosis inducer for cancer treatment in the future.

Study on a Complementary Method to Address the Limitation of Smoke Detectors: Focusing on Carbon Monoxide Sensors

To compensate for the limitations of smoke detectors that frequently emit non-fire alarms, we investigated the carbon-monoxide detection characteristics of smoke detectors using UL 268 fire and non-fire test standards. Large amounts of carbon monoxide were generated during incomplete combustion at the beginning of a fire. Relatively low concentrations of carbon monoxide were also generated under non-fire conditions owing to steam, dust, etc. The response characteristics of general and analog smoke detectors from various manufacturers were analyzed to determine the possibility of linking smoke detectors installed in existing buildings. The experiments revealed that the smoke detectors showed similar reaction characteristics regardless of their manufacturer. However, those equipped with self-made carbon monoxide cross-sensing modules detected different carbon monoxide levels depending on the measurement location or method. Although using a carbon monoxide sensor is effective for distinguishing unwanted fire, additional experiments under various conditions are necessary to establish an appropriate detection range for carbon monoxide based on the response characteristics of the sensor.

Experimental study on the purification capacity of potted plants on low-concentration carbon monoxide in indoor environment.

Indoor low-concentration carbon monoxide (CO) exposure is widespread worldwide, and potted plants may be a potential means for CO purification. The objective is to evaluate common indoor plants' CO purification and tolerance capacities. Epipremnum aureum (Linden ex André) G.S.Bunting, Chlorophytum comosum (Thunb.) Jacques, Spathiphyllum kochii Engl. & K.Krause, and Sansevieria trifasciata Hort. ex Prain with similar sizes were tested in the glass chamber with initial CO concentrations of 10, 25, 50, 100, 200, and 400 ppm, respectively. (1) The CO purification capacity of the four potted plants is ranked as Epipremnum aureum (Linden ex André) G.S.Bunting > Chlorophytum comosum (Thunb.) Jacques > Spathiphyllum kochii Engl. & K.Krause > Sansevieria trifasciata Hort. ex Prain. Under the purification effect of each plant, the CO concentration in the chamber decreases linearly and significantly (p < 0.05), and within a specific time period, the time-weighted average (TWA) CO concentrations can be reduced to below the corresponding permissible exposure limits specified by some countries and organizations. (2) With the increase of the stomatal number of each plant and the increase in CO concentration, the hourly and cumulative absorbed CO of each plant increase linearly and significantly (p < 0.05). (3) With the increase in CO concentration, the CO purification efficiency of each plant decreases exponentially and significantly (p < 0.05). (4) When the CO concentration was ≤ 50 ppm, all plants could effectively purify CO without damage. When the CO concentration was in the range of 100 ~ 400 ppm, within 2 weeks after the 48-h experiment, the leaf tips of Chlorophytum comosum (Thunb.) Jacques and Epipremnum aureum (Linden ex André) G.S.Bunting were damaged one after another, and the damaged leaf area increased with the increase of CO concentration. However, each plant as a whole still survived. This study demonstrated that different species of potted plants can effectively absorb low concentrations of CO to varying degrees, but higher concentrations of CO will damage the survival of specific species of potted plants.

Experimental Investigation of the Effect of Superheated Liquid Fuel Injection on the Combustion Characteristics of Lean Premixed Flames

Abstract The effect of superheated liquid fuel injection on the performance and emissions of a single nozzle combustor was investigated. Combustion of the lean premixed flames was achieved using a combination of jet and swirl as a stabilization method. In a nonreactive setup, the optimum transition temperature of Jet A-1 fuel from liquid to superheated vaporized state was analyzed. In a subsequent reactive setup, a series of tests were conducted with the liquid fuel at low and elevated temperatures. The experiments were conducted at ambient pressure and various air and fuel preheat temperatures, axial swirlers, thermal powers, adiabatic flame temperatures, and flame tube diameters. Concentrations of nitric oxide (NOx) and carbon monoxide (CO) in the flue gas were measured. The operating conditions were systematically selected according to the design of experiments (DOE) method. The results showed that the adiabatic flame temperature caused the most significant change in combustion emissions and the position and shape of the reaction zone, while the superheated fuel injection had only a minor effect because the liquid fuel droplets were largely vaporized before entering the reaction zone through the integration of a swirler and a prefilmer. The use of the axial swirler and prefilmer allowed the combustor to operate in both spray and fully vaporized fuel conditions. As a result, very low emission concentrations of NOx (≈5 ppm) and CO (≈6 ppm) were achieved. The median flame length and height above the burner of the characterized flames showed competitive values of 32 mm and 50 mm, respectively. Lean blowout limits of less than 1500 K were achieved. Two different flame modes were observed during the experiments. By increasing the bulk velocity of the combustor, its hysteresis was resolved, resulting in stable and reliable flames with a wide low-NOx operating range.

Satellite-based assessment of national carbon monoxide concentrations for air quality reporting in Finland

Carbon monoxide (CO) has negative health effects, especially on the respiratory system, when present in large concentrations in ambient air. Therefore, it is one of the 12 air pollutants with monitoring and assessment obligations set by the European Union Ambient Air Quality Directives. With low CO concentrations in Finland, continuous surface measurements are not compulsory but the monitoring and assessment obligation remains. Currently, there are no air quality stations equipped with CO measurements in Finland, and the assessment can only be based on emission estimates.In this work, we demonstrate the use of satellite-based CO measurements from the TROPOspheric Monitoring Instrument (TROPOMI) on-board Sentinel-5 Precursor satellite (S5P) to strengthen the assessment with actual measurements. Averaging satellite measurements over several years reveals the spatial distribution of CO with nationwide coverage in city-scale resolution. Individual satellite measurements, in turn, are used to estimate the surface concentrations and their annual variability in different regions in Finland.For the surface estimates, we used a simple and robust linear model between the satellite measurements and ground-level in-situ measurements. We found that the linear model produces reasonable surface concentration estimates to be used in air quality assessments where the objective is to evaluate whether the monitoring threshold set by the EU is exceeded on a yearly scale. It is noted that cloudiness can cause local data gaps of several days and the low solar elevation angles prevent satellite measurements from 9 to 18 weeks during the winter time in Finland.In Finland, the average total columns show low spatial variability, with only a few high-concentration areas identified. For the last three years, the estimated surface concentrations have stayed well below the lower assessment threshold set by the Air Quality Directive.

Investigation of the Effect of ZnO Film Thickness over the Gas Sensor Developed for Sensing Carbon Monoxide

Herein, a facile and inexpensive ZnO thin film‐based carbon monoxide gas sensor is fabricated using a solution‐process technique. To vary the thickness of ZnO thin films, the precursor solutions of two different molarities, 3 and 5 m, are spin coated over glass substrates. The 3 m ZnO thin‐film device demonstrates more than two times improvement in sensing response as compared to 5 m ZnO films, for 50 ppm carbon monoxide concentration. Additionally, the 3 m ZnO film is found to perform better for low carbon monoxide concentrations, whereas the 5 m ZnO film shows a linear response over a wider range of carbon monoxide concentrations. The gas sensing mechanism and the impact of film thickness on the performance of the device are thoroughly studied and discussed, which may open the doors for the design and development of facile and high‐sensitivity metal oxide‐based gas sensors.

An electronic nose for harmful gas early detection based on a hybrid deep learning method H-CRNN

Among harmful gases, carbon monoxide (CO) has posed a significant threat to human safety due to its concealment and harmfulness. Therefore, it’s imperative for the preservation of human safety to implement early detection for CO concentration. However, traditional methods for gas detection are either plagued by the limitations of insufficient accuracy like electronic nose (E-nose) equipped with relatively simple machine learning algorithms such as vanilla SVM or RNN, or limited by the incapacity to make early prediction such as sensory analysis, which requires a large amount of manpower resources and time. To address this issue, a novel technique, namely H-CRNN, is presented for E-nose to perform early prediction of low concentration CO, leveraging the strengths of convolutional and recurrent neural network to efficiently capture long-term dependencies within data. Also, shortcut connection and a novel gated attention mechanism is applied to enhance the capacity to capture crucial features. Furthermore, a linear process unit has been incorporated to handle the scale insensitivity issue. The experimental results show that the proposed H-CRNN outperforms RNN with a notable average reduction of 50.51% in the root relative squared error and 53.8% in the relative absolute error, and exhibits varying degrees of improvement when compared to state-of-the-art algorithms (TCN, TPA-LSTM, STCN, LSTNet, LSTM). Additionally, the H-CRNN achieved an average accuracy rate of 96.42%, surpassing all other algorithms and demonstrating the highest level of performance. Therefore, our work substantiates the proposed H-CRNN as an applicable method for early prediction of CO concentration.

Short-term exposure to air pollution and emergency room visits for acute respiratory symptoms among adults.

OBJECTIVE: To examine the short-term effect of ambient air pollution on daily acute respiratory emergency room visits among adults.METHODS: A time-series study (June 2017-February 2019) was carried out among adults (≥18 years) visiting a multi-specialty hospital in Delhi. We evaluated the association between the daily levels of particulate matter (PM) <2.5 μm in diameter (PM2.5) and PM <10 μm in diameter (PM10), ozone (O₃), nitrogen dioxide (NO₂), carbon monoxide (CO) and sulphur dioxide and daily count of emergency room (ER) visits for acute respiratory symptoms. Generalised additive model (GAM) was used with the Poisson link function to analyse the associations for 0-1 to 0-7 lag days.RESULTS: A total of 69,400 ER visits were recorded, of which 2,669 were by adults due to acute respiratory symptoms. At 0-7 lag days, an increment of 1 standard deviation in NO₂ and PM2.5 concentration was associated with a percentage increase in acute respiratory ER visits of respectively 53.0% (95% CI 30.84-78.97) and 19.5% (95% CI 4.53-36.65). During 0-7 lag days, a positive trend was observed at higher concentrations of CO (>1.86-3.28 mg/m³), while a negative significant association was observed at low concentrations of CO (<1.171 mg/m³).CONCLUSION: Short-term exposure to ambient NO2 and PM2.5 was associated with acute respiratory emergency visits of adults at lag 0-7 days.

Analysis of the Saw System with the PANI + Nafion Sensing Structure for Detection of Low Concentration Carbon Monoxide

The paper presents a measuring system based on two resonators with a SAWacoustic surface wave. One of the resonators contains a sensor structure consisting of a Nafion layer with a PANI polyaniline nanolayer deposited on it. The sensor structure was tested for carbon monoxide, with a very low concentration (5, 10, 15, 20 ppm) in the atmosphere of synthetic air. The structure sensitivity was tested for two different PANI thicknesses: (100 and 180 nm). The tests were carried out for two different temperatures: 308 K and 315 K. The investigations shows that the measuring system used with the acoustic surface wave together with the proposed sensing layers is sensitive to the presence of low concentration carbon monoxide molecules in the atmosphere of synthetic air.

Room temperature operated flexible La-ZnO/MWCNTs sensor for ppb level carbon monoxide detection

The advancement of gas sensors with ppb level concentration experiences profound challenges. In this research, Lanthanum (La)-Zinc Oxide (ZnO)/multi-walled carbon nanotubes (MWCNTs) composites were successfully fabricated and loaded on a flexible polyimide substrate where interdigitated electrodes (thickness: 300 µm and spacing: 300 µm) were prepared using a laser carbonation technique for room temperature (RT) carbon monoxide (CO) gas detection. The synthesized composites were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy, UV–visible spectrophotometry, x-ray diffraction, and Fourier transform infrared spectroscopy. When compared to the La-ZnO composite, the addition of MWCNTs on the synthesized composite-based sensor exhibited ∼8 times higher response than La-ZnO to 100 ppm CO at 27 °C. The response of the La-ZnO/MWCNTs composite sensors to 20 ppm CO was tested at six different relative humidity (RH) levels ranging from 0% to 90% in the increments of 20% RH. These sensors exhibited humidity tolerant properties, as evidenced by their responses to different humidity levels. Even when exposed to 90% RH, the sensor only showed ∼13% reduction in response compared to 0% RH, indicating that it is a humidity tolerant sensor. Furthermore, the La-ZnO/MWCNTs sensor has excellent selectivity and can detect low CO concentrations of 100 ppb. As a result, the proposed high-performance flexible sensor has a lot of potential for use in wearable devices to sense CO gas at RT for trace level detection.

Carbon monoxide releasing molecule-2 suppresses stretch-activated atrial natriuretic peptide secretion by activating large-conductance calcium-activated potassium channels.

Carbon monoxide (CO) is a known gaseous bioactive substance found across a wide array of body systems. The administration of low concentrations of CO has been found to exert an anti-inflammatory, anti-apoptotic, anti-hypertensive, and vaso-dilatory effect. To date, however, it has remained unknown whether CO influences atrial natriuretic peptide (ANP) secretion. This study explores the effect of CO on ANP secretion and its associated signaling pathway using isolated beating rat atria. Atrial perfusate was collected for 10 min for use as a control, after which high atrial stretch was induced by increasing the height of the outflow catheter. Carbon monoxide releasing molecule-2 (CORM-2; 10, 50, 100 µM) and hemin (HO-1 inducer; 0.1, 1, 50 µM), but not CORM-3 (10, 50, 100 µM), decreased high stretch-induced ANP secretion. However, zinc porphyrin (HO-1 inhibitor) did not affect ANP secretion. The order of potency for the suppression of ANP secretion was found to be hemin > CORM-2 >> CORM-3. The suppression of ANP secretion by CORM-2 was attenuated by pretreatment with 5-hydroxydecanoic acid, paxilline, and 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one, but not by diltiazem, wortmannin, LY-294002, or NG-nitro-L-arginine methyl ester. Hypoxic conditions attenuated the suppressive effect of CORM-2 on ANP secretion. In sum, these results suggest that CORM-2 suppresses ANP secretion via mitochondrial KATP channels and large conductance Ca2+-activated K+ channels.

Вплив низьких концентрацій монооксиду вуглецю на метаболізм ізольованого серця в умовах ішемії-реперфузії

The purpose of the study was to determine the effect of different concentrations of carbon monoxide on the metabolism of isolated mice hearts. Materials and methods. To elucidate the effect of low concentrations of carbon monoxide on the myocardium, we performed retrograde perfusion of isolated hearts of laboratory mice with Krebs-Henseleit solution, which was saturated with carbon monoxide for 5, 10, and 30 minutes. We then determined how different concentrations of carbon monoxide affected coronary volumetric flow rate, myocardial glucose and calcium uptake, creatinine release, and aspartate aminotransferase release. During perfusion, R-wave amplitude and R-R interval were measured using an electrocardiograph. To determine the effect of ischemia on the heart muscle during perfusion with solutions of different concentrations, we measured the area of the affected myocardium after staining with 2,3,5-triphenyltetrazolium chloride. Results and discussion. After these studies, it was found that different concentrations of carbon monoxide had a dose-dependent effect on the isolated mouse heart. However, the dependence of the effects does not follow the pattern «lowest concentration – lowest effect». At the same time, an increase in concentration did not mean an increase in adverse effects on the myocardium. Even on the contrary, the smallest concentration led to increased signs of ischemic myocardial damage. In particular, the use of the solution, through which carbon monoxide was passed for 5 minutes, caused vasoconstrictor effect during perfusion. At the end of reperfusion, vasoconstrictor effect was observed after using a solution through which carbon monoxide was passed for 10 minutes. Increased glucose uptake was observed in the group with 30-minute carbon monoxide permeation against the background of the minimal myocardial creatinine release. In this group there was also a decrease in Ca2+ loss at the beginning of reperfusion (immediately after ischemia). The above phenomenon explains the least degree of ischemic myocardial damage in the isolated mouse heart. The obtained data should be expanded. Since it is difficult to accurately determine the dose of carbon monoxide, then the use of donor compounds is promising. Such compounds include CORM-2 and CORM-3. Under physiological conditions, they decompose in a controlled manner, releasing a specific amount of carbon monoxide. Conclusion. The obtained results indicate that at different concentrations of carbon monoxide can differently influence different structures of cardiomyocyte: at one concentration it binds to calcium channels, other concentrations influence ion channels of plasma membrane, which can explain all these dependencies

Metal-organic frameworks-derived Mn-doped Co3O4 porous nanosheets and enhanced CO sensing performance

Improving the gas-sensing performances of p-type oxide semiconductors is an important research issue. Here, we reported the simple fabrication of bare Co3O4 and Mn-doped Co3O4 porous nanosheets by annealing the Co-based metal-organic frameworks (MOFs) nanosheets precursors synthesized from the ion-assisted solvothermal treatment. Different characterization techniques were adopted to verify the physical and chemical morphologies of the as-prepared samples. The results demonstrate that Mn cations have been successfully doped into the lattice of Co3O4. Besides, these prepared samples were used for detection of carbon monoxide (CO). Results show that 3 mol% Mn-doped Co3O4 nanosheets present enhanced CO-sensing properties [(Rg − Ra)/Ra = 280% to 40 ppm at 125 °C] compared with bare Co3O4 nanosheets. The response reported here for the detection of CO even exceeds those of some n-type oxides under the same conditions. We speculate that the enhanced CO-sensing properties are probably due to the high specific surface area, abundant oxygen vacancies generated by Mn doping, and the relatively high Co3+/Co2+ ratio. The Mn-doped Co3O4 sensor has a huge potential advantage in detecting low concentrations of CO.

Global calibration models for temperature-modulated metal oxide gas sensors: A strategy to reduce calibration costs

Tolerances in the fabrication of metal oxide (MOX) gas sensors lead to inter-device variability in baseline and sensitivity, even for sensors of the same fabrication batch. This has traditionally forced the use of individual calibration models (ICMs) built specifically for each sensor unit, which requires an expensive and time-consuming calibration process and hinders sensor replacement. We propose Global calibration models (GCMs) built using the responses of multiple sensor units, and then applied to a new sensor unit that is not part of the calibration set. GCM have been already successfully applied to transfer calibration models between sensor arrays (electronic noses) for classification tasks. In this work, we investigate the use of such models for regression purposes in temperature-modulated sensors, aiming at the quantification of low concentrations of carbon monoxide (CO) in the presence of variable humidity levels (20–80% r.h. at 26 ± 1 °C). Using a laboratory dataset containing data from 6 replicas of the FIS SB-500–12 model, we evaluate the performance of global models built with data from 1 to 4 sensors when applied to unseen sensor units. Results show that the performance of global models improves with an increasing number of sensors in the calibration set, approaching the performance of individual calibration models (1.38 ± 0.15 ppm for GCM; 1.05 ± 0.24 ppm for ICM), and surpassing their performance only if few calibration conditions per sensor are available (2.09 ± 0.10 ppm for GCM;; 2.76 ± 0.22 ppm for ICM, if only 5 samples per sensor are used).

Precise Identification of the Dimethyl Sulfoxide Triggered Tricarbonyldichlororuthenium(II) Dimer for Releasing CO.

Low concentrations of carbon monoxide (CO) can play vital roles in pharmacological and physiological functions in the human body. The transition-metal carbonyl complexes of the tricarbonyldichlororuthenium(II) dimer [Ru2(CO)6Cl4 (CORM-2)] were proposed as CO-releasing molecules (CORMs) to improve the delivery efficiency of CO for therapeutic effects. The accurate identification of final products for CORMs in solution and the detailed mechanisms of the release of CO were the essential prerequisite for its effective physiological application, which have been deficient. In this study, utilizing the cutting-edge two-dimensional (2D) IR spectroscopy, with the intrinsic vibrational modes and the coupling information on dynamics of intramolecular vibrational energy redistribution (IVR), the final products of A, B, C, and E are accurately identified when CORM-2 is dissolved in dimethyl sulfoxide (DMSO). Furthermore, with the clues on intermolecular interaction and chemical exchange dynamics between different products, the transformations between different products are also directly characterized for the first time. These findings challenge the results from the classic 1D spectroscopic pattern, and they evidently demonstrated that the release of CO from CORM-2 in DMSO was slow and complicated with multiple reaction pathways. Combining with DFT simulations, the detailed mechanisms of release of CO for CORM-2 dissolved in DMSO are schematically proposed, which can significantly contribute to its drug optimization and pharmacological as well as physiological applications.