Carbon Dioxide Treatment Research Articles

Strong and ductile poly (lactic acid) achieved by carbon dioxide treatment at room temperature

Poly (lactic acid) (PLA) is a biodegradable and biocompatible polymer derived from renewable resources that demonstrates an immense potential in replacing fossil-based polymers. Nevertheless, its inherent brittleness and poor thermal resistance significantly restrict its further applications. Developing an environmentally friendly and cost-effective method for strengthening and toughening PLA without sacrificing its other functional properties remains a challenge. In this study, we report a novel method to reinforce PLA by carbon dioxide (CO2) treatment at room temperature. Remarkably, CO2 treatment led to simultaneously enhanced strength, toughness, ductility and thermal resistance. Under 3.5 MPa CO2 treatment, PLA demonstrated the best mechanical performance with tensile strength, ductility, and impact toughness enhanced by 25%, 1214%, and 134%, respectively. Moreover, the Vicat softening temperature was significantly enhanced from 55.8 °C to 155.3 °C. Wide angle X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry elucidate the strengthening and toughening mechanism to be CO2-induced crystallization. The small-angle laser scattering and scanning electron microscope demonstrate the formation of numerous nanorod crystallites, which are responsible for coincidentally enhancing the strength, toughness, and thermal resistance. Thus, CO2 treatment at room temperature provides a green and effective method to provide high-performance PLA products that have immense potential in biomedical, automotive, and other structural applications.

A new sensitization technique combining CO2 and UV treatments for improved neutron dosimetry of CR-39 track detectors

A new sensitization technique combining carbon dioxide and UV treatments was investigated for improved neutron dosimetry of CR-39 track detectors. The detectors were irradiated with an 241Am–Be neutron source in a low-scatter laboratory facility, delivering a personal dose equivalent Hp(10) of 1 mSv. Prior to their chemical etching, the detectors were treated in carbon dioxide at a pressure of 0.6 MPa for 6 days followed by a UV (254 nm) treatment at a distance of 5 cm from the lamp, for 20 h. The opposite, UV followed by carbon dioxide treatment, was also investigated. The qualitative impact of these treatments on the background noise of the detectors, and their track size distributions compared to only carbon dioxide, only UV treated detectors, and untreated ones was analysed. Overall, the technique combining CO2 and UV treatments, independently of their order, increased the sensitivity by about 40% and 120% compared to the UV treatment alone and the untreated detectors, respectively, and reduced approximately 15% compared to the CO2 treatment alone. It also significantly enhanced the average diameter of the tracks compared to both treatments separated, allowing a better distinction between real tracks and the noisy background.

Thermo-electrical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed through supercritical carbon dioxide

In this work, novel electrically conductive cyclic olefin copolymer/exfoliated graphite nanoplatelets foams were prepared through a supercritical carbon dioxide treatment starting from the corresponding unfoamed materials prepared by melt compounding, in order to investigate their thermo-electrical properties. For both unfoamed and foamed samples, the exfoliated graphite nanoplatelets introduction led to a systematic enhancement of the thermal degradation temperature. Dynamic-mechanical thermal analysis revealed that the nanofiller addition promoted an enhancement of the storage modulus and of the glass transition temperature over the whole range of the applied foaming pressures. While for unfoamed materials exfoliated graphite nanoplatelets introduction determined an important decrease of the electrical resistivity, the foaming process induced the breakage of the conductive path, with a consequent increase of electrical resistivity. Evaluation of the surface heating upon voltage application showed that the surface temperature of unfoamed materials could be noticeably increased at relatively low voltage levels, while a less pronounced surface heating could be obtained with the corresponding nanocomposite foams.

Organic solvent free preparation of porous scaffolds based on the phase morphology control using supercritical CO2

Porous polylactide (PLA) scaffolds for tissue engineering were successfully manufactured from co-continuous PLA/polyvinyl pyrrolidone (PVP) blends by combining annealing treatment in supercritical carbon dioxide (scCO2) and porogen leaching. Based on the water solubility of PVP, the employment of organic solvents could be completely avoided during the fabrication of scaffolds. The average pore size ranges from 30 μm to 160 μm with nearly full interconnectivity, and strongly associates with the treatment conditions of annealing process, indicating that the morphology of porous scaffolds can be availably controlled by adjusting CO2 pressure, temperature and annealing time. Moreover, it was found that the average pore size of porous PLA scaffolds fabricated by annealing in scCO2 was larger than that in atmosphere at the same temperature, this signified that porous PLA scaffolds could be achieved at a lower temperature with the introduction of scCO2, which effectively improved the mechanical property of PLA scaffolds.

Critical damage to the cellular organelles of Saccharomyces cerevisiae under sublethal conditions upon high pressure carbon dioxide treatment

ABSTRACTHigh pressure carbon dioxide treatment is a non-thermal pasteurization technique. However, critical damage, resulting from the treatment, to microbial cells has not been observed directly, and the detailed mechanism of the microbicidal activity is not understood. In this study, we analyzed the damage to Saccharomyces cerevisiae organelles, which were visualized using organelle-specific GFP fusion proteins. Yeast strains were subjected to high pressure carbon dioxide treatments at 30°C and 4.0 MPa for 2–8 h. Reduction in yeast cell viability was accompanied by the disruption of endoplasmic reticulum, nuclear membrane, Golgi body, and nucleolus. However, visible damage to the cell membrane was not observed. Fluorescence microscopy was utilized to confirm that high pressure carbon dioxide treatment damaged membranes of major organelles, but not the cell membrane.

Sweet cherry fruit miRNAs and effect of high CO2 on the profile associated with ripening.

157 known and 55 novel miRNAs were found in sweet cherry fruit. MiRNA target genes involved in fruit ripening and the differentially expressed miRNAs under CO2 treatment were identified. MicroRNAs (miRNAs) are short non-coding RNAs and play important functions in many biological processes, including fruit ripening and senescence. In the current study, the high-throughput sequencing and bioinformatics methods were implemented to decipher the miRNAs landscape in sweet cherry fruit. A total of 157 known miRNAs belonging to 50 families and 55 putative novel miRNAs were found. Target genes of the miRNAs were predicted and genes involved in fruit ripening were found, including F-box proteins and TFs such as SPL, TCP, NAC, MYB, ARF and AP2/ERF. And these target genes were further confirmed by degradome sequencing. A regulatory network model was constructed to uncover the miRNAs and their targets involved in fruit ripening and senescence. Importantly, elevated carbon dioxide can significantly postpone the ripening and senescence of sweet cherry fruit and the differentially expressed miRNAs exposed to CO2 were identified. These miRNAs included miR482j, miR6275, miR164, miR166, miR171, miR393, miR858, miR3627a, miR6284, miR6289 and miR7122b, and some of their functions were linked to fruit ripening. This study was the first report to profile miRNAs in sweet cherry fruit and it would provide more information for further study of miRNA roles in the ripening processes and their regulation mechanism underlying the effects of high carbon dioxide treatment on fruit ripening.

Effect of Supercritical Carbon Dioxide Treatment on Gas Permeability of Paulownia Fortunei Heartwood and Sapwood

Many wood species are resistant to penetration of liquids. Impermeability can affect a variety of properties including the ability to deliver preservatives, adhesive bonding, and coating applications. Developing methods for altering this characteristic could help in utilization of impermeable species. One method for altering wood properties is through the use of supercritical carbon dioxide (SC-CO2) which can solubilize a wide range of organic compounds. In this report, we examined the ability of varying SC-CO2 conditions to improve the permeability of Paulownia fortunei. All of the processes tested improved gas permeability and most reduced the frequency of tyloses in the vessels. The results suggest that SC-CO2 could be used to modify the permeability of this species.

Effect of dense phase carbon dioxide treatment on physicochemical and textural properties of pickled carrot

ABSTRACTDense phase carbon dioxide (DPCD), as a new type of non-thermal technologies, has exhibited a remarkable effect on sterilization to improve the quality of many fruits and vegetables, but little known on the pickled carrot. In this study, the effect of DPCD treatment on physicochemical, textural properties and microbiological quality of pickled carrot treatment was investigated. Our results showed that the optimum condition of DPCD treatment was 30 min under 20 Mpa. Compared with thermal treatment, the DPCD treatment significantly improved the storage quality of the pickled carrot at hardness, color, and β-carotene content. Moreover, DPCD treatment increased the total pectin content and reduced the water-soluble pectin content of the pickled carrot without changing the pectin structures and cell-wall composition. Taken together, our study showed that DPCD is a comprehensive technique to improve the quality of the carrot in pickles processing.

Monitoring of Drinking Waters for the Content of Bromide, Iodide, Bromate and Iodate Ions

The monitoring of potable artesian waters of the city of Kyiv for bromide, bromate, iodide, and iodate ions as well as of drinking bottled water for bromides and bromates has been carried out. Bromate, iodide and iodate ions were monitored by the established methods and bromide ions—by the developed method. The stability of the chemical composition of artesian waters of the same horizon is noted. On the other hand, the concentration of bromides and iodides varied 3–4 times in pump-rooms feeding on a mixture of waters from aquifers. For waters containing high concentrations of bromides and iodides, ozonation is counter indicated due to hazard of the formation of carcinogenic bromates and iodates. A conclusion was made that it is more expedient to use carbon dioxide treatment for canning and disinfection of such waters.

Improvement of adhesion of kevlar fabrics to epoxy by surface modification with acetic anhydride in supercritical carbon dioxide

The effect of supercritical carbon dioxide (ScCO2) treatment with acetic anhydride (AA) for Kevlar fabric on the interfacial adhesion and mechanical properties of Kevlar fabric/epoxy composites was investigated. ScCO2 treatment with AA remarkably affects the interfacial adhesion, thus improving mechanical properties. The effects of treating time on the surface modification and mechanical properties of composites were studied. Results demonstrated that the optimal condition is 100°C at 10 MPa for 60 min, as shown by the tensile strength and shear strength of the ScCO2‐treated composites being 21.3 and 47.9% higher than those of the untreated ones, respectively. The mechanical properties demonstrated that ScCO2 treatment provides an efficient and environmentally safe method for surface modification to improve interfacial interaction between the treated fiber and matrix with ScCO2 treatment. POLYM. COMPOS., 40:E920–E927, 2019. © 2018 Society of Plastics Engineers

Synthesis of ZnO nanowires with supercritical carbon dioxide and post heat treatment

Zinc oxide (ZnO) nanowires are used in applications such as gas sensors and solar cells. This work presents a novel synthesis route for ZnO nanowires using supercritical carbon dioxide (scCO2) and post heat treatment. The method used scCO2 and a precursor solution as reactants to form nanowires on a galvanized surface. After the scCO2 treatment, the substrate was heat-treated. The surfaces were characterized with SEM, TEM, EDS, FTIR, XRD and optical spectroscopy. The FTIR results showed that the surface structure had changed from zinc hydroxycarbonate to ZnO during the heat treatment. The nanowires were slightly bent due to the heat treatment according to the SEM images. The presence of ZnO was further confirmed with XRD. The bandgap of the structure was determined by reflectance measurements and showed a value of 3.23 eV. The synthesis method presented in this study offers a unique approach into the formation of ZnO nanowires in a facile, rapid and environmentally friendly process.

Effect of supercritical carbon dioxide processing on Vibrio parahaemolyticus in nutrient broth and in oysters (Crassostrea gigas).

This study aimed to evaluate the technical feasibility of supercritical carbon dioxide (sc-CO2) treatment for Vibrio parahaemolyticus inactivation in oysters (Crassostrea gigas) and in nutrient broth. For this purpose, a variable-volume reactor was used as experimental system and a 23 factorial design was adopted considering the mass ratio between carbon dioxide and the product, pressurization and depressurization rate and pressurization cycles. Through statistical analysis of the experimental data, the mass ratio of 1:0.8 (product:carbon dioxide), depressurization rate of 10.0MPa/min and one cycle of pressurization was determined as the best process condition to eliminate V. parahaemolyticus, and this was the condition used for the inactivation kinetic analysis. Comparison between the inactivation kinetics of V. parahaemolyticus showed that the behavior of this microorganism inactivation depends on the environment in which it operates and its initial count. The results confirm that the supercritical carbon dioxide is effective in inactivating microorganisms in oysters, including pathogenic V. parahaemolyticus, demonstrating the potential of this technology in the food industry.

Inactivation, Aggregation and Conformational Changes of Polyphenol Oxidase from Quince (Cydonia oblonga Miller) Juice Subjected to Thermal and High-Pressure Carbon Dioxide Treatment.

Polyphenol oxidase (PPO) causes the browning reaction in fruits and vegetables and deteriorates the quality. Thermal treatment for enzyme inactivation may result in defects as opposed to high pressure CO2 (HPCD) processing. In this study, the changes in activity, dissociation, aggregation and conformation of purified PPO from thermal and HPCD treated juice were investigated. HPCD exhibited inactivation of PPO at 55–65 °C whereas thermal processing alone at the same temperature resulted in PPO still showing activity. Under thermal treatment at 25 and 65 °C, the browning degree was higher (0.39 and 0.24) than for HPCD-treated juice (0.23 and 0.12). Fluorescence and circular dichroism spectral results indicated that HPCD induced large decreases in intensities, revealing a rearrangement of the secondary structure and destruction of the native configuration of the PPO molecule. The particle size distribution (PSD) pattern revealed structural modification leading to initial dissociation and subsequent aggregation of PPO after HPCD treatment. Polyacrylamide gel electrophoresis (PAGE) analysis exhibited that molecular size of protein was 40 kDa. In conclusion, the HPCD method was found to be more effective than thermal treatment to inactivate PPO. Structural modifications provided better insights into the phenomena of activation and inactivation of PPO.

Responses of Selected C3 and C4 Halophytes to Elevated CO<sub>2</sub> Concentration under Salinity

Halophytes have superior capacity to withstand soil salinity and are appropriate resources to study the mechanism of salt tolerance which can be harnessed to develop crops to withstand salinity. In this communication, we report the effect of salinity (200 mM NaCl) and elevated carbon dioxide (CO 2 ) treatments in tandem, on select halophytes that have different photosynthetic pathways: C3 and C4. The plants were raised in ambient (380 ppm) and enriched (500 ppm) concentrations of CO 2 using a mini-FACE facility. Total chlorophyll content, total soluble sugar concentration, lipid peroxidation level and electrolyte leakage were measured from fresh leaf samples collected at different time points. The results show a positive effect for elevated CO 2 concentration on salt tolerance in both C3 and C4 plants, and indicate that halophytes may benefit from rising atmospheric CO 2 concentration. The results also suggest that C4 halophytes may benefit from the rising atmospheric CO 2 concentration than C3 halophytes.

DcC4H and DcPER Are Important in Dynamic Changes of Lignin Content in Carrot Roots under Elevated Carbon Dioxide Stress.

In our study, isobaric tags for relative and absolute quantification (iTRAQ) was conducted to determine the significantly changed proteins in the fleshy roots of carrots under different carbon dioxide (CO2) treatments. A total of 1523 proteins were identified, of which 257 were differentially expressed proteins (DEPs). On the basis of annotation analysis, the DEPs were identified to be involved in energy metabolism, carbohydrate metabolism, and some other metabolic processes. DcC4H and DcPER, two lignin-related proteins, were identified from the DEPs. Under elevated CO2 stress, both carrot lignin content and the expression profiles of lignin biosynthesis genes changed significantly. The protein-protein interactions among lignin-related enzymes proved the importance of DcC4H and DcPER. The results of our study provided potential new insights into the molecular mechanism of lignin content changes in carrot roots under elevated CO2 stress.

Super-Critical-CO2 De-ECM Process

ABSTRACTExtracellular Matrix (ECM), a natural biomaterials, have recently garnered attention in tissue engineering for their high degree of cell proliferative capacity, biocompatibility, biodegradability, and tenability in the body. Decellularization process offers a unique approach for fabricating ECM-based natural scaffold for tissue engineering application by removing intracellular contents in a tissue that could cause any adverse host responses. The effects of Supercritical carbon dioxide (Sc-CO2) treatment on the histological and biochemical properties of the decellularized extracellular matrix (de-ECM) were evaluated and compared with de-ECM from conventional decellularization process to see if it offers significantly reduced treatment times, complete decellularization, and well preserved extracellular matrix structure. The study has shown that a novel method of using supercritical fluid extraction system indeed removed all unnecessary residues and only leaving ECM. The potential of Sc-CO2 de-ECM progressed as a promising approach in tissue repair and regeneration.

Efficacy of carbon dioxide treatments for the control of the two-spotted spider mite, Tetranychus urticae, and treatment impact on plant seedlings.

To develop a new control method for the two-spotted spider mite (TSSM), Tetranychus urticae, we investigated the effect of controlled atmospheres of carbon dioxide (CO2) on TSSM mortality under different concentrations and treatment periods, and evaluated the impact of treatments on seedlings of five host plants of TSSM. Egg hatching rate of TSSM was reduced to 37.7, 5.4 or 0% after 24h treatment involving concentrations of 16.7, 33.3 or 50%, respectively. Mobile stages (nymphs and adult) of TSSM were completely controlled after 24h treatment at concentrations higher than 33.3%. After 4h at concentrations of 33.3 or 50%, 1st-day survival rate for all mobile stages was 45.3 or 36.0%, respectively, whereas after 8 or 16h treatments, all values were decreased to zero. Seedlings of four major host plants of TSSM (cucumber, eggplant, rape, green peppers) were damaged to varying degrees after 24h at the three concentrations, but strawberry, another host plant, was not damaged. Cucumber suffered the most serious damage, resulting in wilting and death. In conclusion, controlled atmospheres of CO2 can kill TSSM, particularly at high concentrations and with long treatment times. It can be used to control TSSM on strawberry, but should be used cautiously on other host plants.

Comparison of Techniques for Preimplantation Treatment of Osteochondral Allograft Bone.

Articular defects are a major problem with few effective treatment options. Osteochondral allograft (OCA) transplantation can be an effective treatment; however, lack of OCA bone integration can cause failure. This controlled laboratory study was designed to compare clinically applicable methods for marrow element removal and enhanced delivery of bone marrow aspirate concentrate (BMC) to OCA bone. We hypothesized that compressed carbon dioxide (CO2) treatment of OCA bone would result in significantly better marrow element removal, significantly more retention and distribution of viable osteoprogenitor cells, and significantly higher osteoinductive protein elution from OCAs compared with other preimplantation treatments. Fresh humeral heads (n = 24) were harvested and stored for 14 days, then randomly assigned to treatment based on marrow element removal and bone treatment: (standard of care [SOC]) (n = 4) - SOC high-pulse saline lavage, no BMC; (BMC) (n = 5) - saline lavage then canine BMC; (Drill + BMC) (n = 5) - 1.1 mm drill-hole immediately subchondral then saline lavage then BMC injection through drill hole; (Carb + BMC) (n = 5) - saline lavage then CO2 then BMC; or (Saline-Carb + BMC) (n = 5) - saline lavage and CO2 together then BMC. Treated OCAs were cultured for 14 days. On day 3, media were collected, centrifuged to isolate cells, and replaced. Cells were cultured for 11 days for colony forming unit (CFU) determination. OCA media were collected on days 7 and 14 of culture for analysis. On day 14, each graft was assessed for viable cell retention and distribution, and bone marrow element removal. BMC had significantly higher (p = 0.001) viable cell distribution compared with the SOC, Drill + BMC, Carb + BMC, and Saline-Carb + BMC groups. BMC and Drill + BMC had significantly higher (p < 0.05) CFUs than SOC, Carb + BMC, and Saline-Carb + BMC. Drill + BMC and Carb + BMC had the highest media concentrations of the osteoinductive biomarkers. The Carb + BMC and Saline-Carb + BMC groups were associated with significantly superior marrow element removal (p < 0.02) compared with the SOC, Drill + BMC, and BMC groups. Saline irrigation plus saturation with autogenous BMC appears to be the most advantageous preimplantation treatment for OCA transplantation.

Transcutaneous Carbon Dioxide Treatment Is Capable of Reducing Peripheral Vascular Resistance in Hypertensive Patients.

We aimed to investigate the effects of a single carbon dioxide (CO2) treatment on arterial stiffness by monitoring the changes of aortic pulse-wave velocity (PWV) and aortic augmentation index (AIXao), which are indicators of arterial stiffness. PWV and AIXao were measured by an invasively validated oscillometric device. The measurements of stiffness parameters were performed before the CO2 treatment, and at 1, 4 and 8 h after the first treatment. Thirty-one patients were included. No significant changes were found in PWV. AIXao decreased significantly 1 h and 4 h after CO2 treatment compared to baseline values (p=0.034 and p<0.001). AIXao increased 8 h after the CO2 treatment, but remained significantly lower than baseline AIXao values (p=0.016). CO2 treatment is capable of reducing peripheral vascular resistance. We hypothesize that CO2 is not only a temporal vasodilator but is also capable of activating vasodilation pathways.

Fractional Carbon Dioxide Laser in Combination with Topical Corticosteroid Application in Resistant Alopecia Areata: A Case Series.

Introduction:Intradermal steroid injections are used as treatment option in resistant alopecia areata. However, it is difficult and quite painful to treat large areas of alopecia with this modality.Objective:To assess the efficacy and safety profile of a combination of fractional carbon dioxide (CO2) treatment followed by topical corticosteroid application in resistant alopecia areata.Materials and Methods:Ten cases of resistant alopecia areata who had not responded to multiple treatment modalities were treated with fractional CO2 laser followed by topical application of triamcinolone spray (10mg/mL) on the resistant lesions. Patients received 4–8 sessions that were repeated at an interval of 3–4 weeks. Response to treatment was assessed on a quartile physician assessment scale and labeled as excellent (>75% regrowth), good (50%–75% regrowth), fair (26%–50% response), and poor (<25% regrowth).Results:Eight of these ten cases completed the treatment process. Seven of these eight patients had complete recovery of the area treated. One patient however did not show good response even after four sessions. No significant adverse effects were noted in any of the patients.Conclusion:Fractional CO2 laser in combination with topical triamcinolone can prove to be an effective treatment option in resistant alopecia areata.