CO2 Probe Research Articles

A tricorn-rhodamine fluorescent chemosensor for detection of Co2+ ions.

A novel chemosensor TrisRh based on tris(2-aminoethyl)amine and rhodamine 6G is designed and synthesized as a fluorescence turn-on probe for Co2+ ions that is paramagnetic with a property of quenching fluorescence. Rhodamine spirolactam forms are nonfluorescent, whereas, ring-opening of corresponding spirocyclic induced by Co2+ results in strong fluorescence emission. Upon the addition of Co2+ ions, TrisRh can display significant enhancements in absorbance and fluorescence intensity as well as evident colorific transformation, which can be perceived by the naked eye. The association stoichiometry of TrisRh to Co2+ ions was inferred to be 1:1 through Job's plot and electrospray ionization mass spectrometry analysis. The binding model was speculated from Fourier transform infrared spectra and 1 H-nuclear magnetic resonance technologies. Significantly, the limit of detection was determined to be as low as 1.22 nmol. Furthermore, TrisRh can exhibit robust anti-jamming ability against other interference metal ions.

Environment‐Responsive 8‐CF3‐BODIPY Dyes with Aniline Groups at the 3 Position: Synthesis, Optical Properties and RI‐CC2 Calculations

AbstractThe spectroscopic and the photophysical properties of isomeric environment‐sensitive BODIPY derivatives in different solvents are reported. The simultaneous presence of the strong electron‐acceptor CF3 and electron‐donor NH2 group in the structure of BODIPY, as well as the position of the NH2 group on the aryl ring, showed a significant effect on the spectroscopic and fluorescence characteristics of the BODIPY chromophore, both experimentally and theoretically. The comparison of meta and para derivatives (1 a and 1 b) shows that, in both cases, they have a very low quantum yield (Φf) and fluorescence lifetime (τf) in the solvents used (except for n‐hexane), therefore, they are potentially suitable as turn‐on fluorescence sensors. The twisted intramolecular charge transfer (TICT) mechanism was adopted to explain solvate‐induced fluorescence quenching. Besides this, there is a strong pH dependence on the photophysical behavior of the two isomers, which could also lead to applications as pH sensors. On the other hand, only 1 a can be a useful probe for CO2 sensing. Owing to a weaker electron‐donor character of the NHCOMe group in comparison with the NH2 group, the position of the fluorescence “off–on” threshold of BODIPY 1 c and 1 d is shifted to the side of more polar solvents than for 1 a and 1 b.

Total oxidation of trichloroethylene over mayenite (Ca12Al14O33) catalyst

The catalytic oxidation of gaseous trichloroethylene (TCE), mediated by a cost effective mayenite support, was studied in a fixed bed reactor. Mayenite was synthetized by using hydrothermal method and characterized before and after catalytic oxidation experiments by using XRD, N2-sorption (BET), SEM-EDX, TEM and FTIR; the reaction products were analyzed by means of GC–MS, IC and a IR-based CO2 probe. The results showed that mayenite promoted the total oxidation of TCE in the temperature range 300–500°C, where TCE was quantitatively converted in CO2 and chlorine. The mayenite catalyst showed high recyclability and could be used for several reaction cycles without any loss of activity and selectivity. Owing to its characteristics, mayenite was found to be a promising catalyst for the TCE total conversion and remediation.

A method to monitor urinary carbon dioxide in patients with septic shock

Severe sepsis and septic shock are life-threatening conditions with mortality rates exceeding 31% (Levy et al., 2012) [1]. Septicemia was the most expensive US hospital condition in 2011 (Torio and Andrews, 2006) [2]. Urinary carbon dioxide may provide rapid, clinically useful information about a patient’s status, empowering physicians to intervene earlier and improve septic shock mortality. The objective of this paper is to validate a protocol with a Severinghaus-type CO2 probe for the measurement of urinary CO2 of septic shock patients. This protocol includes (i) sampling urine from a Foley catheter in an intensive care unit setting, (ii) storing samples until analysis at a separate facility, (iii) calibration of the Severinghaus-type CO2 sensor, and (iv) measuring urinary CO2 levels. We discuss the preparation and stability of standard solutions, storage of urine samples, and the performance characteristics of the Severinghaus type CO2 sensor in relation to mock urine samples, urine quality control standards, and urine samples from healthy volunteers as well as patients in severe sepsis or septic shock. We report the influence of the sample pH, temperature, and ionic strength on the precision and accuracy of the measurements of urinary CO2 levels and show that the protocol developed for the quantitative assessment of urinary CO2 levels is adequate for the analysis of urine samples collected from a Foley catheter.

Method of Measurement of CO2 Adsorbed into α-Cyclodextrin by Infra-Red CO2 Probe

A simple CO2 probe system for quantifying CO2 gas adsorbed in solid matrix of α-cyclodextrin powder (α-CD) by measuring the gas concentration in the headspace was developed and validated. The essential components of this system are an infrared CO2 probe and an air tight chamber equipped with a two-fan system to uniformly mix the relatively high density CO2 gas. First, a known weight of dry ice (considered as pure CO2) was used to create different amounts of CO2 in the headspace of the chamber, and the resultant gas concentrations were measured by the probe and gas chromatography. The gas concentrations measured by both methods were quite similar (R2 = 0.9950), and the calculated amount of dry-ice in the headspace using the probe was highly comparable to the amount of dry ice initially added in the chamber (R2 = 0.9970). This system was then tested to measure adsorbed CO2 content in CO2-α-CD complexed powder by using water injection to release CO2 from the complexed powder into the headspace. The measured results using this system were quite similar (R2 = 0.9972) to those determined by a conventional acid-base titration method.

A DFT study of the acid–base properties of anatase TiO2 and tetragonal ZrO2 by adsorption of CO and CO2 probe molecules

We have performed a comparative study of the acid–base characteristics of the surfaces of anatase TiO2 and tetragonal ZrO2. To this end we performed DFT+U calculations on CO and CO2 probe molecules adsorbed both on terraces and steps of the two oxides. For titania, CO adsorption results in a moderate adsorption energy (about −0.3eV) and in a positive shift of the CO stretching frequency (about +40cm−1), typical of Lewis acid sites, with no clear difference in the acidity between terraces or steps. For zirconia we found a similar CO binding energy as for titania, and a CO vibrational shift that depends on the location of the Zr cation: negligible on terraces, similar to TiO2 on steps. We conclude that the acidic properties are similar in the two oxide surfaces. Things are different for CO2 adsorption. On titania the interaction is weak and surface carbonates compete with physisorbed CO2, indicating a weak basic character. On the contrary, on zirconia three types of stable carbonates have been identified. Their vibrational frequencies are consistent with IR measurements reported in the literature. The most stable species forms on steps of the t-ZrO2 surface and consists of a CO32− unit which lies flat on the surface with the O atoms pointing towards three Zr ions. The species forms spontaneously by extraction of a lattice oxygen by an incoming CO2 molecule. The different reactivity points towards a much more pronounced basic character of zirconia compared to titania, at least if measured by CO2 adsorption.

Potentiometric Monitoring of Co2+ Ion at Nano Scale Based on Hydrazinecarbothioamide Derivatives by Fabrication of Coated Pyrolytic Graphite Electrode

Hydrazinecarbothioamide derivative based ligands 2,2′-(((ethane-1,2-diylbis-(oxy))bis(3-methoxy-4,1-phenylene))bis-(methanylylidene))bis(hydrazinecarbothioamide) (L1), 2,2′-(((propane-1,3-diylbis(oxy))bis(3-methoxy-4,1-phenylene))bis-(methanylylidene))bis-(hydraznecarbothioamide) (L2) and 2,2′-((((oxybis(ethane-2,1-diyl))bis(oxy))bis(3-methoxy-4,1-phenylene))bis(methanylylidene))bis(hydrazinecarbothioamide) (L3) were synthesized and investigated as monitoring probe for Co2+ ion. Fabricated coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE) were prepared and CPGE explored the best performance with optimized membrane composition L2: PVC: 1-CN: KTpClPB ≡ 6:35:56:3 (w/w, mg). CPGE showed low detection limit of 6.1 × 10−9 mol L−1, Nernstian compliance (29.4 ± 0.6 mV decade−1 of activity), wide working pH range (3.0–8.5) and fast response time (7 s). The sensor is practically applicable in real samples and used as an indicator electrode in the potentiometric titration of Co2+ ion with EDTA.

Comparación de la eficacia de dos técnicas de crioterapia para el tratamiento de las verrugas plantares

Objective. To compare two techniques of Cryotherapy for clinical effectiveness, pain, and effect on the quality of life of patients when treating plantar warts. Method. A quasi-experimental matched subject study was conducted. Twenty subjects with a newly diagnosed plantar wart were recruited. Subjects were matched for confounding variables in relation to site of lesion, gender and age, and were divided into two groups. Group A (n=10) were treated using the CO2 Gun & Probe technique whilst Group B (n=10) were treated using the Portable N2O pressurized spray technique. The plantar warts were measured at time 0 (before treatment) and Time 1(3 weeks following treatment) using a metre ruler. The Foot Function Index and the Visual Analog Scale for pain assessment during treatment were also used. Results. The study found no significant difference in the effectiveness (p= 0.387), pain caused during treatment (P=0.855) and FFI scores (p=0.172) for total change in QOL in the study group when comparing both treatments. However, comparison of the mean scores showed that the CO2 Gun & Probe method was slightly more effective in reduction of size. Pain during treatment was almost identical when using both techniques. The FFI scores on all 3 subscales (Pain, Disability and Activity Limitation) showed a larger increase in the CO2 Gun & probe method, when compared to the pressurized N2O Portable device. Conclusions. Although this study has found no significant difference between two different techniques of cryotherapy, mean differences have indicated that the CO2 Gun & Probe technique is more effective in reducing the size of the warts when compared to the N2O Pressurized Spray Technique; however the CO2 Gun & Probe technique caused a larger impact on quality of life. Recommendations from this study suggest that careful consideration is required when selecting a treatment for plantar warts and furthermore patients should be advised on the likely outcomes of each treatment before any intervention.

A colorimetric organic chemo-sensor for Co2+in a fully aqueous environment

A new highly selective and sensitive colorimetric chemosensor 1 for Co(2+) was developed. The receptor 1 sensed Co(2+) by changing its color from yellow to orange in aqueous solution. Moreover, 1 could be used as a practical, visible colorimetric test kit for Co(2+).

Vitamin B6cofactor based fluorescent probe for sensing an anion (F−) and cation (Co2+) independently in a pure aqueous medium

A new highly selective and sensitive bifunctional fluorescent probe for Co2+and F−ions has been derived from a vitamin B6cofactor and the response mechanism has been analyzed using DFT calculations.

Examination of acid–base properties of solid catalysts for gas phase dehydration of glycerol: FTIR and adsorption microcalorimetry studies

Acid–base properties of zirconia and titania based materials were investigated by FTIR spectroscopy of CO2 and pyridine probe molecules adsorption. Catalytic performance of the catalysts was also tested in the gas phase dehydration of glycerol with the intention of investigating relationship between catalytic activity and nature of acidic and basic active sites. Results confirmed preferential Brönsted-acid catalyzed route of acrolein formation. Moreover, clear evidence of the effect of the nature of basic sites to selectively yield acetol was presented, basic OH groups being more selective than basic oxide ions.

Kinetic behavior of carbon dioxide absorption in diethanolamine/ionic-liquid emulsions

Room-temperature ionic liquids (RTILs) have been found to induce precipitation of CO2-captured carbamate product in case of amine–RTIL systems that may lead to an efficient carbon dioxide capture process. Here we have studied the kinetic behavior of CO2 absorption in (mutually immiscible) DEA–[hmim][Tf2N] blends in a laboratory scale stirred-cell reactor at ambient pressure (∼1atm) to assess the effects of amine concentration (⩽2M DEA), CO2 partial pressure, agitation speed (1500–4500rpm), and temperature variation (25–41°C). A CO2 probe was used to monitor the change in gaseous CO2 volume ratio during the absorption experiments.

Soil gas carbon dioxide probe: laboratory testing and field evaluation

An automated semi-continuous on-line instrument has been developed to measure CO2 gas concentrations in the vadose zone. The instrument uses semi-permeable polymer tubing (CO2 probe) for diffusion based sampling, coupled to an infra red sensor. The system operated automatically by intermittently purging the CO2 probe, which was installed in the vadose zone, with a non-CO2 gas at a low flow rate. The gas exiting the CO2 probe was monitored at the ground surface using a miniature infra red sensor and the response related to the vadose zone soil gas CO2 concentration. The in situ CO2 probes provided a reliable monitoring technique under long-term (18 months) aggressive and dynamic field conditions, with no interference observed from non-CO2 gases and volatile organic compounds. The probes provided data that were comparable to conventional grab sampling techniques without the labour-intensive sample collection and processing associated with these conventional techniques. Also, disturbance to vadose zone CO2 profiles from repeated grab samples during long-term semi-continuous monitoring could potential be reduced by using the diffusion based sampling technique.

DIURNAL AND SEASONAL VARIATION OF MEASURED ATMOSPHERIC CO2 AT DEHRADUN DURING 2009

Abstract. Atmospheric carbon dioxide (CO2) is the major greenhouse gas. We analysed the diurnal trend and seasonal variations of atmospheric Carbon Dioxide (CO2) measured at Dehradun during 2009. The measurements are taken from the Vaisala CO2 probe installed at the top of the IIRS building. A distinct diurnal cycle with seasonal variations is present in these measurements. Diurnal cycle exhibits a half sinusoidal variation with decreasing phase during sunrise to afternoon and increasing phase during afternoon to sunset. CO2 mostly remains constant with higher values during the night. The largest negative anomaly with respect to the annual mean varies between +/-20 ppmv with positive anomaly during the night time and negative anomaly during the day time. The cause of such variation could be attributed to the local ecosystem activity. During the day time the sinking of CO2 through the photosynthesis dominates its release through autotrophic and heterotrophic respiration. On the other hand, photosynthesis has been ceased during the night time and respiration only controls the night variation of CO2.There exists significant change on the diurnal cycle of CO2 in different seasons during the year. The maximum rapid decrease in CO2 concentration in early morning hours is due to photosynthetic activity during the monsoon periods (maximum in August -8ppm). During monsoon period rapid night time increase of CO2 is observed due to the enhancement of respiration. An inverse relationship exist between model simulated net ecosystem productivity and CO2 deviations on monthly basis. This diurnal and seasonal variations in situ CO2 are in confirmation with model simulated results.

Rain Induced Changes in Carbon Dioxide Concentrations in the Soil–Lake–Brook Continuum of a Boreal Forested Catchment

The numerous water bodies and their riparian zones in the boreal zone are crucial to lateral carbon transport and can thus be very significant for carbon cycle on the landscape level. Therefore, we installed automatic measurement systems with Vaisala CARBOCAP CO2 probes (Vaisala Oyj, Vantaa, Finland) in the riparian zone soil matrix around a small headwater lake, in the lake itself, and in the outflowing brook and followed the seasonal and diurnal variation in CO2 concentration as well as rain event‐driven changes in this natural‐state soil–lake–brook continuum in Southern Finland. Seasonal variation was greatest and concentrations highest deep in the soil and in the lake, but were also noticeable in the brook. On the other hand, diurnal variation was highest in shallow soil layers and the lake surface. In the brook, the influence of the riparian zone superseded that of the lake at less than 150 m distance, which resulted in wider variation and higher concentrations of CO2. After the rain event, the normal diurnal pattern was changed, and the CO2 concentration in the soil increased as water filled the soil pores and slowed down the diffusion. Even though the water with lower CO2 concentration from the lake diluted the CO2 concentration in the brook, the input from the soil dominated the flow after the rain and concentrations increased. On an annual basis, the flow of terrestrial dissolved inorganic carbon (DIC) into the aquatic ecosystem was 1–13% of terrestrial net ecosystem production (NEP).

Novel methods to diagnose obstructive sleep apnea in children

Sleep-disordered breathing encompasses a spectrum of disorders that increase in severity from snoring to obstructive sleep apnea (OSA). OSA is a clinical disorder that requires a polysomnogram (PSG) to make the diagnosis. The PSG is the gold standard to confirm OSA. Alternative diagnostic tests are presented to supplement the clinical evaluation with objective information when evaluating the snoring child. Diagnostic tests to identify the anatomical site of obstruction are also discussed.

Direct and continuous dissolved CO2 monitoring in shallow raceway systems: From laboratory to commercial-scale applications

Direct and continuous measurement of dissolved CO2 (dCO2) is crucial for intensive aquaculture, especially in shallow raceway systems (SRS). In this work the performance of a portable dissolved CO2 probe analyzer was tested for the effects of different aqueous solutions, pure oxygen injection and agitation. Laboratory results showed significant (p<0.05) solution effects on probe performance for low (10–20mgL−1) and high (30–50mgL−1) dCO2 concentrations. Globally performance was better in deionized water, followed by marine fish farm water and artificial seawater. Accuracy and response time were the parameters most affected by the type of solution tested. Linearity was always observed (R2=0.995–0.999). The probe was sensitive to 1mgL−1 dCO2 increments for concentrations <6mgL−1 in artificial seawater. Pure oxygen injection did not affect probe readouts, and agitation was needed for better accuracy and response time. In real marine SRS with tanks in series dCO2 dynamics was revealed using the probe coupled to a developed flow cell. A prototype SRS was built and used to study dCO2 dynamics without endangering cultivated fish. Generally, results obtained indicate that the probe tested although precise, is better suited for discrete, single-point dCO2 monitoring, being a limited resource for the special needs of shallow raceway systems. As SRS represent a paradigm change in aquaculture, new water quality monitoring strategies and instrumentation are needed, especially for dCO2. Fiber optic sensors can be a solution for continuous, multipoint monitoring, thus contributing to the understanding of water quality dynamics in hyperintensive aquaculture systems.

Bacterial survival studies to assess the efficacy of static pile composting and above ground burial for disposal of bovine carcases

To assess the survival of bacteria during two alternative means of cattle carcase disposal in windrows: static pile composting (SPC) and above ground burial in soil (AGB), under temperate climate conditions on agricultural land, compared to surface disposal as the control method. Bacteriological reference materials (pooled bovine faeces in permeable nylon bags and lyophilized cultures of Escherichia coli in glass ampoules) were positioned above and below each of 33 beef cattle carcases (250-300 kg). Temperatures at these sites were monitored with data loggers, while temperature and CO(2) probes were applied repeatedly at varying depths along the windrows. Aliquots of each reference material were cultured from three randomly selected animals from the SPC and AGB group and from all three control animals on five occasions (at 28, 56, 84, 126 and 182 days). SPC was highly efficacious in the destruction of coliforms in faeces and E. coli in ampoules within 28 days, while AGB was not significantly better than controls until 84 days, and bacteria in reference materials above the AGB carcases were still viable after 182 days. Temperature probes and loggers showed SPC provided sustained temperatures of 55-70°C, while AGB did not reach temperatures of 30°C, and the temperature differences correlated with bacteriological findings. In relation to emergency disease management, SPC can be successfully applied to eliminate pathogenic bacteria in cattle carcases, but AGB is unsuitable for carcase disposal. In emergency, animal disease outbreaks in temperate climates requiring large-scale ruminant carcase disposal, SPC can be successfully applied for the destruction of micro-organisms.

Comparative performance of CO2 measuring methods: Marine aquaculture recirculation system application

Many methods are available for the measurement of dissolved carbon dioxide in an aqueous environment. Standard titration is the typical field method for measuring dissolved CO2 in aquaculture systems. However, titrimetric determination of dissolved CO2 in marine water aquaculture systems is unsuitable because of the high dissolved solids, silicates, and other dissolved minerals that interfere with the determination. Other methods used to measure dissolved carbon dioxide in an aquaculture water included use of a wetted CO2 probe analyzer, standard nomographic methods, and calculation by direct measurements of the water's pH, temperature, and alkalinity. The determination of dissolved CO2 in saltwater based on partial pressure measurements and non-dispersive infra-red (NDIR) techniques with a CO2 gas analyzer are widely employed for oceanic surveys of surface ocean CO2 flux and are similar to the techniques employed with the head space unit (HSU) in this study. Dissolved carbon dioxide (DC) determination with the HSU using a infra-red gas analyzer (IRGA) was compared with titrimetric, nomographic, calculated, and probe measurements of CO2 in freshwater and in saltwater with a salinity ranging from 5.0 to 30ppt, and a CO2 range from 8 to 50mg/L. Differences in CO2 measurements between duplicate HSUs (0.1–0.2mg/L) were not statistically significant different. The coefficient of variation for the HSU readings averaged 1.85% which was better than the CO2 probe (4.09%) and that for the titrimetric method (5.84%). In all low, medium and high salinity level trials HSU precision was good, averaging 3.39%. Differences existed between comparison testing of the CO2 probe and HSU measurements with the CO2 probe readings, on average, providing DC estimates that were higher than HSU estimates. Differences between HSU and titration based estimates of DC increased with salinity and reached a maximum at 32.2ppt. These differences were statistically significant (P<0.05) at all salinity levels greater than 0.3ppt. Results indicated reliable replicated results from the head space unit with varying salinity and dissolved carbon dioxide concentrations.

Soil CO2 concentrations and their implications in conventional and no-tillage agricultural fields

Soil CO2 concentrations to a depth of 50 cm depth were monitored with Vaisala CO2 probes from June 2004 to May 2005 in conventionally plowed and no-tillage agricultural plots and found to be generally higher in the former than the latter. Soil CO2 concentrations were also higher in summer and lower in winter, but were modulated by harvesting and the application of crop residues. Analysis of diurnal variations in soil CO2 concentrations, soil CO2 effluxes, and soil temperatures revealed distinct differences between plots. The relative amplitudes of the variation in CO2 concentrations peaked at a soil depth of 5 cm. Soil CO2 concentrations were higher when there was higher soil water content after precipitation, while soil CO2 effluxes were lower under the same circumstances. These two results relate to the lower diffusivity at higher soil water content, which restricts CO2 efflux, leading to higher soil CO2 concentrations. Calculations reveal that in the shallower soil layer (0-5 cm), CO2 production was greater in no-tillage plots, whereas in the deeper layer (15-25 cm), it was greater in conventional plots.