Cold CO2 Research Articles

Effect of thermal shock on the permeability and seismic wave velocity of the caprock and reservoir during CO2 injection

The injection of relatively cold CO2 into warmer reservoirs causes rapid cooling of the host reservoir and the overlying caprock in the near wellbore region. This rapid cooling may cause thermal fracturing, which may potentially lead to escape of the CO2. We have here investigated the effect of thermal fracturing, due to rapid quenching, on the permeability and P-and S-wave velocities of caprock and reservoir samples from the In Salah CO2 storage site, Krechba field, Algeria. Injection of CO2 may have cooled the caprock and reservoir by up to 65°C. Laboratory experiments were conducted where caprock and reservoir samples were heated to various temperatures (50, 150, 250, 350 and 500°C) and rapidly quenched to room temperature (20°C). Permeability and P- and S-wave velocities were measured pre- and post-thermal treatment at effective pressures up to 60 MPa. Backscattered scanning electron microscopy analysis revealed that most of the fracturing is mainly within siderite (Fe carbonate). X-ray diffraction analysis showed that the minerals chlorite (Fe-clay) and siderite were destroyed in specimens heated to 500°C. Specimens that were rapidly quenched by 230°C experienced less than half an order of magnitude increase in permeability and very small to negligible changes in the P- and S-wave velocities. We conclude that the effect of thermal shock fracturing in the Krechba field due to CO2 injection is negligible because the change in the permeability and velocities are insignificant for the predicted maximum degree of cooling (approximately 65°C) of the formation due to CO2 injection. The conclusion of the lack of thermal quenching effects due to CO2 injection at In Salah may be applicable to all global Carbon Capture and Storage prospects.

Obstruction of infrared signature with cold gases

The idea of infrared signature reduction by injecting cold gas between the source and observer has been investigated. Statistical narrow band coefficients of ethylene have been generated from HITRAN spectroscopic database and proposed to attenuate radiation on the 8–14 μm spectral region whereas CO2 is employed for 3–5 μm wavelength band suppression. Dilution of ethylene with CO2 also suppresses the flammability and guarantees safe operation. Several 1-D test cases are solved to validate the developed solver, and the proposed method is tested on 1-D and 3-D problems. The results satisfactorily show that a significant and safe radiance reduction can be achieved with cold CO2 diluted ethylene injection between the exhaust and observer on the whole spectrum.

Thermodynamic analysis and evaluation of a novel trans-critical CO2 power system incorporating partial condensation, sub-cooling, and recompression

Trans-critical CO2 Rankine cycle (TRC) is a promising technology that converts heat into power generation with its safe and environment-friendly characteristics. However, the low critical temperature of CO2 restricts the practical application of TRC, which requires a relatively low temperature heat sink to ensure the CO2 condensation. In addition, the heat capacity mismatch between hot and cold CO2 streams in the recuperator restricts the performance improvement of traditional recuperative trans-critical CO2 Rankine cycle (RTRC). In this study, a novel partial condensation trans-critical CO2 recompression cycle (PCRC) is proposed to simultaneously address the issues of condensing difficulty and low performance. Thermodynamic analysis and optimization models for both PCRC and RTRC are formulated and a solution algorithm is developed. Case studies are explored to validate the superiority of PCRC over traditional RTRC in thermal efficiency and operation flexibility. Influence of key parameters on the PCRC performance is also investigated to reveal the improvement mechanism over RTRC. Furthermore, sensitivity analysis is carried out on the upper operation pressure, heat source parameter, and heat sink parameter of the PCRC to determine its operational flexibility.

Examining the individual and additive effects of cold storage and CO2 narcosis on queen survival and reproduction in bumble bees

Diapause is a pre-programmed arrest of development allowing insects to survive in unfavorable environments. In adult insects, diapause termination is often followed by a reallocation of macronutrients and a transition to reproduction, and in some insects, this transition can be achieved using narcosis with CO2. However, whether CO2narcosis and diapause act in concert to affect reproduction remains unknown. Here, we investigated the separated and combined effects of diapause and CO2on female reproduction in queens of the common eastern bumble bee Bombus impatiens. Queens were treated with CO2 following a cold storage period (zero days, two weeks, two and four months) and were compared with untreated queens at the same timepoints for survival, colony initiation, egg-laying latency, and offspring production. We found that both CO2 and a period of at least two months in cold storage induced a transition to egg laying in gynes, and as expected, survival decreased with cold storage length. When CO2 and cold storage were combined, CO2narcosis positively affected egg laying in the earlier timepoints but its impact diminished following a longer cold storage. These data suggest that the impacts of CO2narcosis and cold storage are partially additive, and application of CO2 is effective only after a short cold storage. It further demonstrates that CO2 has complex effects on insect reproduction that are independent from diapause.

Numerical analysis of fracture deformation and instability during CO2 geological sequestration using a THM-XFEM coupled model

Fracture deformation and instability during long-term CO2 geological sequestration in abandon reservoirs is simulated with a thermal-hydro-mechanical model. The two-phase in non-isothermal condition is used both in matrix and fracture, and thermoelastic and poroelastic deformation are all taken into account. The extended finite element method is employed to solve the strong discontinuity problem involving thermal-hydro-mechanical coupling. The S-W equation of state and transport equation are chosen to characterize CO2 phase change. CO2 geological sequestration in abandoned-fractured reservoir with high water-cut is discussed with a two-dimensional model. The analysis of fracture deformation shows that CO2 geological sequestration has a great effect on fracture deformation and instability. Fracture aperture, deformation and the effective fluid pressure in fracture are highly affected by the water residual saturation and injected temperature difference. The analysis of fracture instability presents that mode I mainly appears in the fracture propagation, and propagation prefers to occur in fracture near the injection wellbore. The higher CO2 phase pressure when cold CO2 injection into reservoirs with low water residual saturation can promote fracture propagation 1–2 years in advance. Fracture aperture is enhanced but fracture instability time would be delayed due to the thermal stress.

Syngas evolution and energy efficiency in CO2 assisted gasification of ion-exchanged pine wood

In this study, the effect of ion-exchange sodium concentration on gasification process was first studied in a semi batch rector at 1073 K. In addition, four specific temperatures from 973 to 1223 K were further examined during gasification, with focus on the amounts of syngas components’ yield, energy yield, energy efficiency as well as the CO2 consumption for the raw and ion-exchange samples. Results showed that pine wood with higher ion-exchange sodium resulted in higher CO and syngas yield, while the acid washed sample provided the lowest syngas yield. Presence of ion-exchange sodium showed a strong catalytic effect on gasification, which enhanced the syngas yield and energy generation. Besides, the increase in gasification temperature led to enhanced syngas yield, cold gas efficiency and CO2 consumption, mainly due to its promotional effect on Boudouard reaction. Highest energy yield of 7.18 and 19.88 kJ/g, cold gas efficiency of 40.66% and 112.65%, and CO2 consumption of 0.74 and 1.75 g/g were found for the ion-exchange sample at 973 K and 1223 K, respectively. Overall energy efficiency showed a trend of first an increase followed by a decrease with time. The peak value of the ion-exchange sample was shifted to longer reaction time as compared to the raw sample. A maximum overall energy efficiency of 50.52% was obtained at 26.3 min for the ion-exchange sample at 1223 K. Therefore, temperature also offers a promotional effect on energy efficiency, which is of significant value in practical applications. This research provides a new insight to achieve maximum energy yield and efficiency with the help of ion-exchange species, in addition to the advantages of effective CO2 utilization.

Thermodynamic Characteristics of cold and hot non-condensable gases simultaneously flowing along vertical wellbore

In recent years, thermal non-condensable gas injection was widely used in petroleum industry to enhance oil recovery. However, the research on the heat transfer process and thermodynamic characteristics analysis along wellbore is almost in blank under the condition of cold and hot non-condensable gases simultaneously flowing in wellbore. In this paper, a complicated mathematical model was established considering simultaneous hot and cold gases injected into tube and annulus. Meanwhile, a coupling calculation method was introduced based on temperature equations, pressure equations, and thermodynamic properties. The model can be used to analyze temperature and pressure distribution, the depth of phase transition, the heat transfer pattern and the thermodynamic characteristics. The accuracy of the model was verified and sensitivity analysis of some parameters was conducted. It is found that: (a) The injection method (hot N2 is injected into tube and cold CO2 is injected into annulus) is optimal, which produces fainter heat loss and maintains higher total energy; (b) Some factors, such as, the injection temperature, the injection mass ratio of hot and cold gases, and the injection velocity, have a dramatic effect on temperature and pressure distribution, fluid thermophysical parameters, and fluid phase state. (c) According to the calculation results, the optimal temperature of nitrogen is 350 °C, the optimal injection mass ratio of N2 to CO2 is 15:1, and the optimal injection velocity of CO2 is 120 t/d; (d) The temperature along wellbore changes intensively at the beginning of injection while it becomes stable when the injection time exceeds 10 days. The ingenious coupling model with intricate iterative processes can perfectly simulate the injection process of hot and cold non-condensable gases and obtain the temperature and pressure distribution along wellbore, which can provide tremendous guidance and assistance for injection operations in the oilfield.

Complete Equation of State Thermal Formulation for Simulation of CO2 Storage

Summary Storage of carbon dioxide (CO2) in depleted gas reservoirs or large aquifers is one of the available solutions to reduce anthropogenic greenhouse gas emissions. Numerical modeling of these processes requires the use of large geological models with several orders of magnitude of variations in the porous media properties. Moreover, modeling the injection of highly concentrated and cold CO2 in large reservoirs with the correct physics introduces numerical challenges that conventional reservoir simulators cannot handle. We propose a thermal formulation based on a full equation of state (EoS) formalism to model pure CO2 and CO2 mixtures with the residual gas of depleted reservoirs. Most of the reservoir simulators model the phase equilibriums with a pressure-temperature-based formulation. With this usual framework, it is not possible to exhibit two phases with pure CO2 contents. Moreover, in this classical framework, the crossing of the phase envelope is associated with a large discontinuity in the enthalpy computation, which can prevent the convergence of the energy conservation equation. In this work, accurate and continuous phase properties are obtained, basing our formulation on enthalpy as a primary variable. We first implement a new phase-split algorithm with input variables as pressure and enthalpy instead of the usual pressure and temperature, and we validate it on several test cases. This algorithm can model situations in which the mixture can change rapidly from one phase to the other at constant pressure and temperature. Then, treating enthalpy instead of temperature as a primary variable in both the reservoir and the well modeling algorithms, our reservoir simulator can model situations with pure or near pure components, as well as crossing of the phase envelope that usual formulations implemented in reservoir simulators cannot handle. We first validate our new formulation against the usual formulation on a problem in which both formulations can correctly represent the physics. Then, we show situations in which the usual formulations fail to represent the correct physics and that are simulated well with our new formulation. Finally, we apply our new model for the simulation of pure and cold CO2 injection in a real depleted gas reservoir from the Netherlands.

The Implications of the Diving Response in Reducing Panic Symptoms.

Increased CO2 sensitivity is common in panic disorder (PD) patients. Free divers who are known for their exceptional breathing control have lower CO2 sensitivity due to training effects. This study aimed to investigate the immediate effects of cold facial immersion (CFI), breath holding and CO2 challenges on panic symptoms. Healthy participants and patients with PD were subjected to four experimental conditions in a randomly assigned order. The four conditions were (a) breath-holding (BH), (b) CFI for 30 s, (c) CO2 challenge, and (d) CO2 challenge followed by CFI. Participants completed a battery of psychological measures, and physiological data (heart rate and respiration rate) were collected following each experimental condition. Participants with PD were unable to hold their breath for as long as normal controls; however, this finding was not significant, potentially due to a small sample size. Significant reductions in both physiological and cognitive symptoms of panic were noted in the clinical group following the CFI task. As hypothesized, the CFI task exerted demonstrable anxiolytic effects in the clinical group in this study by reducing heart rate significantly and lessening self-reported symptoms of anxiety and panic. This outcome demonstrates the promise of the CFI task for clinical applications.

Warm and humidified insufflation gas during gynecologic laparoscopic surgery reduces postoperative pain in predisposed patients—a randomized, controlled multi-arm trial

BackgroundPostoperative pain remains a common problem in gynecologic laparoscopy, especially in head zone-related regions, triggered by intra-abdominal pressure during capnoperitoneum. Humidified and prewarmed insufflation gas may ameliorate pain and be beneficial.MethodsThis prospective randomized controlled parallel group multi-arm single-center study investigated the effects of temperature and humidity of insufflation gas on postoperative pain during gynecologic laparoscopy with a duration ≥ 60 min. Female participants (18—70 years) were blinded and randomly assigned—computer generated—to either insufflation with dry cold CO2 with forced air warming blanket (“AIR”), humidified warm gas without forced air warming blanket (“HUMI”), or humidified warm gas with forced air warming blanket (“HUMI +”). We hypothesized that using humidified warm gas resulted in lower pain scores and less analgesic consumption. The primary endpoint postoperative pain was assessed for different pain localizations every 12 h during 7 days after surgery. Secondary endpoints were demand for painkillers and epidural anesthetics, length of stay in recovery room, and hospital stay. (Registration: ClinicalTrials.gov NCT02781194—completed).Results150 participants were randomized. Compared to group “AIR” (n = 48), there was significantly less pain in group “HUMI +” (n = 48) in the recovery room (− 1.068; 95% CI − 2.08 to − 0.061), as well as significantly less ibuprofen use at day two (− 0.5871 g ± 0.258; p-value = 0.0471). Other variables did not change significantly. Stratification for presence of endometriosis or non-previous abdominal surgery in patient history revealed significantly less pain in both groups “HUMI” (n = 50) and “HUMI +” versus group “AIR.” Related side effects were not noted.ConclusionIn the overall population, the use of warm, humidified insufflation gas did not yield clinically relevant effects; however, in predisposed patients with endometriosis and who could otherwise expect high pain levels, warm and humidified gas may be beneficial.

Computational fluid dynamics study of CO2 dispersion with phase change of water following the release of supercritical CO2 pipeline

Accidental release of pressurized CO2 pipeline in carbon capture and storage involves the interaction of phase change and heavy-gas dispersion. However, the effect of the phase change of water vapor in air on the performance of cold CO2 dispersion is usually neglected. In this study, a three-dimensional two-phase computational fluid dynamics (CFD) model is developed to evaluate the cold CO2 dispersion by considering the phase change of water. A phase-change model based on the homogeneous relaxation model is used to describe the evaporation and condensation of water. The effects of terrain roughness, atmospheric stability, and turbulence models on the dispersion are also considered. The numerical results show that the model that uses the k–ω turbulent equations is superior to the other models. The results in which the phase change of water is considered exhibit a better agreement with the data from the experiments than those that do not consider it. The model is subsequently used in urban areas, which results in over-predicted CO2 concentration in the near field and under-predicted CO2 concentration in the far field when the phase change of water vapor is considered than that when it is neglected. Therefore, we proposed that the phase change of water vapor in the atmosphere should not be overlooked in the more accurate modeling of cold CO2 dispersion.

A coupled thermo-hydro-mechanical model for simulating leakoff-dominated hydraulic fracturing with application to geologic carbon storage

A potential risk of injecting CO2 into storage reservoirs with marginal permeability (≲ 10 mD (1 mD = 10−15 m2)) is that commercial injection rates could induce fracturing of the reservoir and/or the caprock. Such fracturing is essentially fluid-driven fracturing in the leakoff-dominated regime. Recent studies suggested that fracturing, if contained within the lower portion of the caprock complex, could substantially improve the injectivity without compromising the overall seal integrity. Modeling this phenomenon entails complex coupled interactions among the fluids, the fracture, the reservoir, and the caprock. We develop a simple method to capture all these interplays in high fidelity by sequentially coupling a hydraulic fracturing module with a coupled thermal-hydrological-mechanical (THM) model for nonisothermal multiphase flow. The model was made numerically tractable by taking advantage of self-stabilizing features of leakoff-dominated fracturing. The model is validated against the PKN solution in the leakoff-dominated regime. Moreover, we employ the model to study thermo-poromechanical responses of a fluid-driven fracture in a field-scale carbon storage reservoir that is loosely based on the In Salah project's Krechba reservoir. The model reveals complex yet intriguing behaviors of the reservoir-caprock-fluid system with fracturing induced by cold CO2 injection. We also study the effects of the in situ stress contrast between the reservoir and caprock and thermal contraction on the vertical containment of the fracture. The proposed model proves effective in simulating practical problems on length and time scales relevant to geological carbon storage.

Comparison between Conventional Microdissection and CO2 Laser in the Treatment of Vocal Cord Polyp

Background: Vocal cord polyp usually arises from the epithelium and the lamina propria. Minimally invasive dissection procedures are employed to treat these vocal cord polyp for an effective outcome. Two types of microsurgical techniques were developed gradually and practiced namely, the conventional laryngeal microsurgery, which involves the use of cold instruments and the laryngeal laser micro-surgery.
 Objective: To compare the conventional cold dissection and CO2 laser methods in treatment of vocal cord polyp.
 Methods: A randomized prospective study was conducted at the Department of Otolayngology- Head & Neck Surgery, at Bangabondhu Sheikh Muzib Medical University (BSMMU) between July 2017 and June 2019. A total of 60 cases were studied on the following parameters: a. Visual analysis on stroboscopy b. Voice analysis –GRBAS (grade, roughness, breathiness, asthenia, strain) indices c. Duration of surgery d. Peroperative bleeding.
 Results: During first postoperative assessment, both groups had the normal symmetrical waves, while 50% of cases still had aperiodicity but all patients had the near normal periodicity in the second postoperative assessment. Regarding glottic closure, during preoperative assessment, almost all patients had incomplete glottic closure due to mass lesion as polyps. During first postoperative assessment, glottic closure was found to be better in group B (83% of cases) than group A (76% of cases), while during second postoperative assessment, all patients of both groups had around 95% glottic closure. The mean duration oflaser technique (7.1 ± 1.1 minutes) was less than the conventional technique time (15.6 ± 1.9 minutes), also mean of operative bleeding of laser technique (zero pack) is less than the conventional two(2 packs).
 Conclusion: There is no significant difference between both groups in all parameters except operative time and bleeding, as laser technique has less time and clear field.
 Bangladesh J Otorhinolaryngol; April 2021; 27(1): 17-24

Placental gas exchange during amniotic carbon dioxide insufflation in sheep.

Insufflation of the amniotic cavity with carbon dioxide (CO2 ) is used clinically to improve visibility during complex fetoscopic surgery. Insufflation with heated, humidified CO2 has recently been shown to reduce fetal hypercapnia and acidosis in sheep, compared with use of cold and dry CO2 , but the underlying mechanisms are unclear. The aim of this study was to investigate whether differences in placental CO2 and oxygen (O2 ) exchange during insufflation with heated and humidified vs cold and dry CO2 could explain these findings. Thirteen fetal lambs at 105 days of gestation (term, 146 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and instrumented with an umbilical artery catheter, an umbilical vein catheter and a common umbilical vein flow probe. Arterial and venous catheters and flow probes were also inserted into the maternal uterine circulation. Six ewes were insufflated with cold, dry CO2 (22°C; 0-5% humidity) and seven with heated, humidified CO2 (40°C; 95-100% humidity) at 15 mmHg for 180 min. Blood-flow recordings and paired arterial and venous blood gases were sampled from uterine and umbilical vessels. Rates of placental CO2 and O2 exchange were calculated. After 180 min of insufflation, fetal survival was 33% (2/6) using cold, dry CO2 and 71% (5/7) using heated, humidified CO2 . By 120 min, fetuses insufflated with heated, humidified CO2 had lower arterial CO2 levels and higher arterial pH compared to those insufflated with cold, dry gas. Insufflation decreased significantly placental gas exchange in both groups, as measured by rates of both (i) fetal CO2 clearance and O2 uptake and (ii) maternal O2 delivery and CO2 uptake from the fetal compartment. Lower arterial CO2 and higher pH levels in fetuses insufflated with heated and humidified, compared to cold and dry, CO2 could not be explained by differences in placental gas exchange. Instead, heated and humidified insufflation appeared to reduce fetal CO2 absorption from the uterus, supporting its use in preference to cold, dry CO2 . © 2019 International Society of Ultrasound in Obstetrics and Gynecology.

CO2 Injection in Depleted Reservoirs: Analysis, Modelling

CO2 geological storage is key in the battle against global warming considering the amount of CO2 that can be removed from the atmosphere and stored underground. CO2 geological storage is targeting at least three different subsurface resources: depleted hydrocarbons reservoirs, deep saline aquifers or unconventional formations such as coal seams or basalts. Unlike the latter solution, interests have mostly been focused on deep saline aquifers and depleted oil & gas reservoirs. If deep saline aquifers are preferred in terms of storage resources as larger volumes can be handled, there are unknowns and the geological structures can be poorly defined. For depleted hydrocarbons reservoirs, knowledges are larger, but resources are less. CO2 geological storage in depleted reservoirs gives the possibility of reusing existing infrastructures and can lead to cost reductions. At date, there are six large scale operational CO2 Geological Storage projects: Sleipner (Norway), Snohvit (Norway), Quest (Canada), Gorgon (Australia), Decatur (USA) and Tomakomai (Japan, stopped); none of them injects into depleted reservoirs, but into saline aquifers. Operational projects targeting CO2 injection within depleted hydrocarbon reservoirs are very few and of a smaller scale. The most prominent projects are Rousse CO2 pilot in France (2009-2013) in which gaseous CO2 was injected at well head, and K12-B gas field in the Netherlands (2004-2017), in which supercritical CO2 was injected at well head. In the Oil & Gas industry, transport pipelines generally flow single-phase hydrocarbon fluid, and preferred phase is liquid to avoid cavitation effects and limit volumes to be transported. When it comes to CO2 geological storage, CO2 is transported in liquid phase by pipeline or by boat compressed at circa -51°C and 7 bars. To optimize the volume stored underground, injection of supercritical CO2 is recommended (dense phase). Potential detrimental side effects of injecting CO2 in depleted reservoirs are the Joule-Thomson effect, the risk of forming CO2 hydrate and creation of thermal induced fractures. To fight those adverse effects, most of the projects (such as those in Northern Sea offshore depleted reservoirs) consider heating the CO2 at the well head before injecting. Heating CO2 before injection could under certain conditions be a killing factor for the project; not only from a cost point of view, but also from a life cycle analysis point of view. Thus, injecting “cold CO2” within depleted reservoirs (compared to “hot CO2” injection) should also be considered. “Cold CO2 injection” (4°C or 10°C depending of seabed temperature) into a low pressure reservoir (circa 10-20 bar) leads to a phase transition from liquid to liquid/gas within the wellbore resulting in temperature profile that can reach negative values near the wellhead and/or at the perforation level. From a well integrity point of view, impacts must be assessed, completions and downhole safety valves materials must be carefully evaluated and qualified. From a well injectivity point of view, possible impairment due to hydrates formation within the near wellbore must be assessed in detail and operational procedures have to be defined accordingly. Based on these considerations, risk analysis is required to address well integrity and well injectivity stakes with appropriate tools. A review of current off-the-shelf commercial software and tools for near wellbore modelling has demonstrated that approaches for cold CO2 injection into depleted reservoir cases are not completely satisfactory. In order to be able to represent properly the CO2 thermodynamic specificities, simulators need to be coded using pressure and enthalpy (P H) primary variables, instead of pressure and temperature (P T), which is not the case for most of them. For the few of them coded in P-H mode, their internal limitations are incompatible with P T ranges of cold CO2 injection into depleted reservoirs (pressures range from 5 up to 300 bar, temperatures range from 50°C up to 150°C). A dedicated numerical tool has thus been developed by TOTAL. It consists of an analytical numerical approach enabling to model thermodynamically the phenomenon occurring during cold CO2 injection, within wellbore and reservoir.

A Study of Temperature Effects in the Bunter Closure 36, a Potential Large-scale CO2 Storage Site in UK

This paper reports on numerical thermal studies of cold CO2 injection into the Bunter Closure 36 prospect, analysing temperature effects during the injection and assessing the time required by the aquifer to recover the initial natural temperature. Fluid flow properties and pressure variation in the injection area are analysed, assessing different cooling scenarios that might occur depending on the thermal properties of the geology surrounding the storage site. Different thermal modelling approaches are presented, discussing some aspects of input data and setup. Information from thermal simulation studies might feed injection design, geo-mechanical analysis, and monitoring of CO2 migration.

‘도태랑’ 토마토의 이산화탄소 및 이산화염소 복합 처리에 따른 저장기간 중 품질 향상 효과

Pink-colored tomatoes have higher sugar content than the red-colored tomatoes; however, they are more prone to fruit cracking during cultivation and transportation owing to their lower firmness. Short-term high CO2 and ClO2 gas treatments were used to prevent chilling injury and reduce decay incidence during the cold storage of tomato ‘Dotaerang’ fruits (Solanum lycopersicum Mill. cv. Dotaerang). Harvested tomatoes were treated with 30% CO2, 60% CO2, and 30% CO2 combined with 10 ppm ClO2 (mixed with ambient air) for 3 h, and then stored at 4°C and 20°C. Fruit quality was assessed after storage at 4°C for 14 days and/or transferred to 20°C for 3 days (14+3 days), and 20°C for 13 days. Cold storage and CO2 treatment inhibited the softening process and delayed fruit surface color development and lycopene accumulation in tomatoes (‘Dotaerang’). A high positive correlation was found between the a* value and lycopene content of tomatoes during storage. The chilling injury index was confirmed to be reduced by cold storage and 30% CO2 treatment. In particular, the 30% CO2 combined with 10 ppm ClO2 treatment was highly effective in preventing the decay of tomatoes during long-term cold storage after harvest. These results suggest that pre-storage high CO2 and/or ClO2 treatment and low-temperature storage can effectively extend the shelf life and improve the quality of pink-colored tomato ‘Dotaerang’ fruits.

A reaction mechanism for vibrationally-cold low-pressure CO2 plasmas

The use of plasmas for CO2 utilization has been under investigation in recent years following a wave of environmental awareness. In this work, previously published experimental results on vibrationally cold CO2 plasmas are modelled to define a reaction mechanism, i.e. a set of reactions and rate coefficients validated against benchmark experiments. The model couples self-consistently the electron and heavy particle kinetics. In turn, the simulated results are validated against measurements taken in CO2 DC glow discharges in a relatively large range of experimental conditions: at pressures from 0.4 to 5 Torr, reduced electric fields ranging from 50 to 100 Td and gas flowing from 2 to 8 sccm. The model predicts the measured values of product formation (CO and O) as well as discharge power and electric field. After validation, a thorough analysis of the model’s results is presented, including: electron properties, species densities, power distribution into different excitation channels and main creation and destruction mechanisms of the main species. It is shown that, although vibrational populations are low, they have a significant effect on the electron properties and thus on the electric field and conversion. Moreover, the shape of the EEDF is significantly dependent on the dissociation degree. The role of electronically excited states on CO2 dissociation is also analyzed, showing that the first electronic excited state of CO can have a beneficial or detrimental effect in further producing CO and O in the discharge.

1H-NMR-Based Analysis for Exploring Knee Synovial Fluid Metabolite Changes after Local Cryotherapy in Knee Arthritis Patients.

Rehabilitation using cryotherapy has widely been used in inflammatory diseases to relieve pain and decrease the disease activity. The aim of this study was to explore the metabolite changes in inflammatory knee-joint synovial fluids following local cryotherapy treatment (ice or cold CO2). We used proton nuclear magnetic resonance (1H NMR) spectroscopy to assess the metabolite patterns in synovial fluid (SF) in patients with knee arthritis (n = 46) before (D0) and after (D1, 24 h later) two applications of local cryotherapy. Spectra from aqueous samples and organic extracts were obtained with an 11.75 Tesla spectrometer. The metabolite concentrations within the SF were compared between D1 and D0 using multiple comparisons with the application of a false discovery rate (FDR) adjusted at 10% for each metabolite. A total of 32 metabolites/chemical structures were identified including amino acids, organic acids, fatty acids or sugars. Pyruvate, alanine, citrate, threonine was significantly higher at D1 vs D0 (p < 0.05). Tyrosine concentration significantly decreases after cryotherapy application (p < 0.001). We did not observe any effect of gender and cooling technique on metabolite concentrations between D0 and D1 (p > 0.05). The present study provides new insight into a short-term effect of cold stimulus in synovial fluid from patients with knee arthritis. Our observations suggest that the increased level of metabolites involved in energy metabolism may explain the underlying molecular pathways that mediate the antioxidant and anti-inflammatory capacities of cryotherapy.

Effects of Warmed and Humidified CO2 Surgical Site Insufflation in a Novel Experimental Model of Magnetic Compression Colonic Anastomosis.

Background. Pneumoperitoneum insufflation with warmed and humidified carbon dioxide (WH-CO2) can prevent heat loss and increase tissue oxygenation. We evaluated the impact of localized WH-CO2 insufflation on the anastomotic healing process. Methods. Sixty male Wistar rats were randomized: Group 1 (control, n = 12), Group 2 (cold and dry CO2, CD-CO2, n = 24), and Group 3 (WH-CO2, n = 24). A magnetic compression side-to-side colonic anastomosis was performed under 60-minute local abdominal CO2 flow insufflation. Animal temperature was recorded. IL-1, IL-6, and CRP levels were assessed before and after insufflation and on postoperative day (POD) 7 and POD 10. Endoscopic follow-up was performed on POD 7 and POD 10. A burst pressure (BP) test of the specimen was performed on POD 10, and histopathological analysis was then performed. Metabolomics of the anastomotic site was determined. Results. Seven rats (5 CD-CO2 group, 1 WH-CO2 group, and 1 control group) died during the survival period. Necropsies revealed intestinal occlusions (n = 2). One additional rat from the CD-CO2 group was sacrificed on POD 7 due to intestinal perforation. The postoperative course was uneventful in the remaining cases. There was no difference in BP among the groups. Thermal monitoring confirmed that WH-CO2 insufflation was effective to reduce heat loss. IL-1 levels were statistically and significantly lower on POD 10 in the WH-CO2 group than the CD-CO2 group but not lower than the control group. CRP levels, histopathology, and metabolomics did not show any difference between the 3 groups. Conclusions. WH-CO2 was effective to preserve core temperature. However, it did not improve anastomotic healing.