Combined Carbon Dioxide Research Articles

Potential of a CO2-Responsive supramolecular drug-carrier system as a safer and more effective treatment for cancer

We combined carbon dioxide (CO2)-responsive cytosine-containing rhodamine 6G (Cy-R6G) as a hydrophobic anticancer agent with hydrogen-bonded cytosine-functionalized polyethylene glycol (Cy-PEG) as a hydrophilic supramolecular carrier to construct a CO2-responsive drug delivery system, with the aim of enhancing the responsiveness of the system to the tumor microenvironment and thus the overall effectiveness of anticancer therapy. Due to self-complementary hydrogen bonding interactions between cytosine units, Cy-R6G and Cy-PEG co-assemble in water to form spherical-like nanogels, with Cy-R6G effectively encapsulated within the nanogels. The nanogels exhibit several distinctive physical features, such as widely tunable nanogel size and drug loading capacity for Cy-R6G, intriguing fluorescence properties, high co-assembled structural stability in normal aqueous environments, enhanced anti-hemolytic characteristics, sensitive dual CO2/pH-responsive behavior, and precise and easily controllable CO2-induced release of Cy-R6G. Cytotoxicity assays clearly indicated that, due to the presence of cytosine receptors on the surface of cancer cells, Cy-R6G-loaded nanogels exert selective cytotoxicity against cancer cells in pristine culture medium, but do not affect the viability of normal cells. Surprisingly, in CO2-rich culture medium, Cy-R6G-loaded nanogels exhibit a further significant enhancement in cytotoxicity against cancer cells, and remain non-cytotoxic to normal cells. More importantly, a series of in vitro experiments demonstrated that compared to pristine culture medium, CO2-rich culture medium promotes more rapid selective internalization of Cy-R6G-loaded nanogels into cancer cells through cytosine-mediated macropinocytosis and thus accelerates the induction of apoptosis. Therefore, this newly developed system provides novel avenues for the development of highly effective CO2-responsive drug delivery systems with potent anticancer capabilities.

Triple combination of fractional carbon dioxide laser, 308-nm excimer lamp, and platelet-rich plasma in refractory vitiligo: A randomized split-body comparative study

Objectives: Vitiligo significantly impacts patients’ quality of life. Current evidence indicates that combination therapy results in faster improvement, enhancing patient adherence to treatment and leading to higher satisfaction among patients. In this study, we compare the efficacy of combined fractional carbon dioxide (FCO2) laser and excimer lamp with platelet-rich plasma (PRP) or topical tacrolimus in patients with refractory vitiligo. Material and Methods: This is a prospective, single-blind, randomized split-body clinical trial involving 41 patients with resistant focal patches of vitiligo vulgaris. Each patient had two similar lesions randomly assigned to receive either a combination of FCO2 laser, excimer lamp, and intradermal PRP injections or a combination of FCO2 laser, excimer lamp, and topical 0.1% tacrolimus (applied twice daily for 12 weeks). The FCO2 laser and PRP treatments were administered in three monthly sessions, and the excimer lamp was used twice a week over 12 weeks. The efficacy of treatment was assessed based on the physician’s assessment and patient’s satisfaction Results: Despite significant improvement in both treatment groups during the course of treatment, the PRP group showed significantly superior efficacy (more than 50% improvement) compared to the tacrolimus group (56.1% and 26.8%, respectively). Furthermore, the PRP group exhibited greater improvement in resistant acral areas compared to the tacrolimus group (51.2% and 19.5%, respectively). Conclusion: The combination of FCO2, an excimer lamp, and PRP demonstrates superior efficacy, particularly in resistant acral areas. As a result, this combination can be recommended in difficult-to-treat areas in patients with vitiligo.

Modelling and optimization of combined supercritical carbon dioxide Brayton cycle and organic Rankine cycle for electricity and hydrogen production

Hydrogen as a clean fuel, is key energy carrier for sustainable development, and its production via water electrolysis is most desirable for its carbon free nature. Nuclear power provides good opportunity to satisfy the huge energy demand associated with the process, in addition to electrical power generation. Modelling an efficient and cost effective nuclear based power and Hydrogen cogeneration system and optimizing it to enhance its performance is the core academic problem addressed in the present study. It proposes a power plant cycle aided by a nuclear reactor, providing 300 MW thermal power input. Supercritical CO2 Brayton cycle is used as the main cycle, instead of traditional Helium Brayton cycle or steam Rankine cycle. To increase the cycle efficiency, by reducing the compression work and by reducing the cold source loss, main compression intercooling and waste heat recovery by an Organic Rankine Cycle (ORC) is introduced together with recompression Brayton cycle arrangement. The power coming from recovered waste heat goes to a Proton Exchange Membrane Electrolyzer (PEME), which facilitates the production of Hydrogen by splitting water via electrolysis. Additional attention is given to ORC fluid selection by employing and comparing the performance of widely acknowledged R245fa together with its more eco friendly replacements, R1233Zd(E) and R1234Ze(Z). The evaluation of the system performance is conducted through the lenses of Energy, Exergy, and Economics. Essential parameters are scrutinized to gauge their impact on two pivotal objectives. Overall Exergy Efficiency(ηex) takes care of the thermodynamic performance and the economic aspect is scrutinized by Levelized Cost of Energy (LCOEn). Notably, by employing R245fa as the ORC working fluid, the system attains peak Energy efficiency of 42.13% and Exergy efficiency of 58.32%, and a minimum LCOEn of 0.063 USD/kWh. Of all the components associated with the system nuclear reactor tops the chart for maximum exergy destroyed(40.8% of total) as well as maximum investment cost(65.7% of total). Pump contributes least to exergy destruction(0.03% of the total) and heat exchangers hold least share(1.1% of total) for investment cost. Furthermore, a multiobjective optimization exercise is executed to fine-tune the system’s operational parameters. This optimization results in a 3.12% increase in Overall Exergy Efficiency and a 9.79% decrease in LCOEn compared to the base operating condition with R245fa used as the ORC fluid. The ηex & LCOEn in best possible operating condition are 58.25% & 0.0645 USD/kWh using R245fa as ORC fluid, 58.23% & 0.0645 USD/kWh using R1233Zd(E) as ORC fluid and 58.22% & 0.0644 USD/kWh using R1234Ze(Z) as ORC fluid. If same amount of electrical Power is supplied to PEME for both with and without ORC configuration, having an ORC is advantageous both in terms of superior Exergy Efficiency and lower LCOEn. The proposed configuration is also economically more lucrative with higher Net Present Value(NPV) and Benefit to Cost Ratio(BCR). For example, when PEME power input for both the cases is 10 MW, proposed system has NPV = 201.79 Million USD & BCR = 1.70 compared to NPV = 164.03 Million USD & BCR = 1.58 for without ORC configuration. Even if in without ORC configuration, no electrical power is supplied to the electrolyzer, adding an ORC to produce Hydrogen will still achieve maximum 1.57% Exergy Efficiency increment, compared to only electrical power production by sCO2 Brayton cycle. It is seen that in base condition, the NPV is still superior for the proposed configuration (203.03 to 189.32 Million USD), and the BCR dips only slightly from 1.72 to 1.71.

Clinical Study of Carbon Dioxide Laser and Pelvic Floor Function Exercise for Urinary Incontinence Complicated by Genitourinary Syndrome of Menopause.

Urinary incontinence is common in patients with genitourinary syndrome of menopause (GSM). A retrospective cohort study was conducted to analyse the clinical efficacy of carbon dioxide laser combined with pelvic floor functional exercise for GSM with urinary incontinence, aiming to provide evidence for its clinical treatment. Patients diagnosed with GSM and urinary incontinence and admitted to our hospital from January 2021 to December 2022 were included and allocated to a control group (pelvic floor function exercise) and combined group (carbon dioxide laser combined with pelvic floor function exercise). Confounding factors among the groups were balanced by the propensity score matching method. The clinical efficacy, GSM scale scores, urinary indicators, urinary incontinence quality of life scale (I-QOL) scores and the degree of urinary incontinence of the groups were compared. A total of 192 patients were included in this study, and 36 cases were included in each group after the propensity scores were matched. No statistical difference in baseline data was found between the groups (p > 0.05). The combined group had higher total effective rate and I-QOL scores but lower GSM symptom scale scores than the control group. Urination during daytime and nighttime was less frequent in the combined group than in the control group, which showed a lower degree of urinary incontinence (p < 0.05). Combining carbon dioxide laser treatment with pelvic floor exercises is potentially effective for patients with GSM and urinary incontinence. This combined approach not only alleviated GSM and urinary incontinence symptoms but also reduced the severity of urinary incontinence, promoted bladder function recovery and enhanced overall quality of life.

Preparation of low-fat and shape-preserving walnut via combined carbon dioxide osmotic treatment and subcritical fluid defatting

A sequential process, CO2 osmotic treatment combined with subcritical fluid defatting was developed to prepare low-fat walnut kernel preserving shape integrity. The influence of operating parameters involving osmotic pressure and subcritical butane defatting repeats on the defatting effect has been investigated. CO2 osmotic at 25 MPa resulted in defatting rate as 37.12% and minimum perfect kernel rate (81.48%). Increase of defatting repeats from one to three times led to exploding quantities of defatting rate (from 9.98% to 40.61%) but no significant varies of perfect kernel rate (p > 0.5). With the increase of defatting rate, the amount of oil bodies in walnut cells decreased, and defatting rate presented negative correlated with hardness and chewiness of products. Hexanal, nonanal and heptaldehyde were the predominant volatile compounds. After defatting, they may be removed as accompanying components and showed a slight downward trend. However, results of electronic nose revealed that there was no significant difference among flavor of walnut with different defatting rate (p > 0.5). Slight defatting caused significant variations in the taste of walnuts. As the defatting rate exceeded 18.65%, products expressed similar taste. Overall, coupling CO2 osmotic treatment with subcritical fluid defatting proved to be great potential for application in shape-preserving defatting.

Role of BP-ANN in simulating greenhouse gas emissions from global aquatic ecosystems via carbon component-environmental factor coupling

Inland waters (IW), estuarine areas (EA), and offshore areas (OA) function as aquatic systems in which the transport of carbon components results in the release of greenhouse gases (GHGs). Interconnected subsystems exhibit a greater greenhouse effect than individual systems. Despite this, there is a lack of research on how carbon loading and its components impact GHG emissions in various aquatic systems. In this study, we analyzed 430 aquatic sites to explore trade-off mechanisms among dissolved organic carbon (DOC), particulate organic carbon, dissolved inorganic carbon (DIC), and GHGs. The results revealed that IW emerged as the most significant GHG source, possessing a comprehensive global warming potential (GWP) of 0.78 ± 0.08 (10−2 Pg CO2-ep ha−1 year−1) for combined carbon dioxide, methane, and nitrous oxide. This surpassed the cumulative potentials of EA and OA (0.35 ± 0.05 (10−2 Pg CO2-ep ha−1 year−1)). Additionally, structural equation modeling indicated that GHG emissions resulted from a combination of carbon component loading and environmental factors. DOC exhibited a positive correlation with GWPs when influenced by biodegradable DOC. Total alkalinity and pH influenced DIC, leading to elevated pCO2 in aquatic systems, thereby enhancing GWPs. Predictive modeling using backpropagation artificial neural networks (BP-ANN) for GWPs, incorporating carbon components and environmental factors, demonstrated a good fit (R2 = 0.6078, RMSEaverage = 0.069, p > 0.05) between observed and predicted values. Enhancing the estimation of aquatic region feedback to GHG changes was achieved by incorporating corresponding water quality parameters. In summary, this study underscores the pivotal role of carbon components and environmental factors in aquatic regions for GHG emissions. The application of BP-ANN to estimate greenhouse effects from aquatic regions is highlighted, providing theoretical and experimental support for future advancements in monitoring and developing policies concerning the influence of water quality on GHG emissions.

CO2-facilitated upcycling of polyolefin plastics to aromatics at low temperature.

Plastics are one of the most produced synthetic materials and largest commodities, used in numerous sectors of human life. To upcycle waste plastics into value-added chemicals is a global challenge. Despite significant progress in pyrolysis and hydrocracking, which mainly leads to the formation of pyrolysis oil, catalytic upcycling to value-added aromatics, including benzene, toluene and xylene (BTX), in one step, is still limited by high reaction temperatures (>500°C) and a low yield. We report herein CO2-facilitated upcycling of polyolefins and their plastic products to aromatics below 300°C, enabled by a bifunctional Pt/MnOx-ZSM-5 catalyst. ZSM-5 catalyzes cracking of polyolefins and aromatization, generating hydrogen at the same time, while Pt/MnOx catalyzes the reaction of hydrogen with CO2, consequently driving the reaction towards aromatization. Isotope experiments reveal that 0.2kg CO2 is consumed per 1.0kg polyethylene and 90% of the consumed CO2 is incorporated into the aromatic products. Furthermore, this new process yields 0.63kg aromatics (BTX accounting for 60%), comparing favorably with the conventional pyrolysis or hydrocracking processes, which produce only 0.33kg aromatics. In this way, both plastic waste and the greenhouse gas CO2 are turned into carbon resources, providing a new strategy for combined waste plastics upcycling and carbon dioxide utilization.

Symptomatic post COVID patients have impaired alveolar capillary membrane function and high VE/VCO2

BackgroundPost COVID-19 syndrome is characterized by several cardiorespiratory symptoms but the origin of patients’ reported symptomatology is still unclear.MethodsConsecutive post COVID-19 patients were included. Patients underwent full clinical evaluation, symptoms dedicated questionnaires, blood tests, echocardiography, thoracic computer tomography (CT), spirometry including alveolar capillary membrane diffusion (DM) and capillary volume (Vcap) assessment by combined carbon dioxide and nitric oxide lung diffusion (DLCO/DLNO) and cardiopulmonary exercise test. We measured surfactant derive protein B (immature form) as blood marker of alveolar cell function.ResultsWe evaluated 204 consecutive post COVID-19 patients (56.5 ± 14.5 years, 89 females) 171 ± 85 days after the end of acute COVID-19 infection. We measured: forced expiratory volume (FEV1) 99 ± 17%pred, FVC 99 ± 17%pred, DLCO 82 ± 19%, DM 47.6 ± 14.8 mL/min/mmHg, Vcap 59 ± 17 mL, residual parenchymal damage at CT 7.2 ± 3.2% of lung tissue, peakVO2 84 ± 18%pred, VE/VCO2 slope 112 [102–123]%pred. Major reported symptoms were: dyspnea 45% of cases, tiredness 60% and fatigability 77%. Low FEV1, Vcap and high VE/VCO2 slope were associated with persistence of dyspnea. Tiredness was associated with high VE/VCO2 slope and low PeakVO2 and FEV1 while fatigability with high VE/VCO2 slope. SPB was fivefold higher in post COVID-19 than in normal subjects, but not associated to any of the referred symptoms. SPB was negatively associated to Vcap.ConclusionsIn patients with post COVID-19, cardiorespiratory symptoms are linked to VE/VCO2 slope. In these patients the alveolar cells are dysregulated as shown by the very high SPB. The Vcap is low likely due to post COVID-19 pulmonary endothelial/vasculature damage but DLCO is only minimally impaired being DM preserved.

Treatment of Acne Keloidalis Nuchae by Simply Combining Two Conventionally Available Modalities: Ablation with Carbon Dioxide Laser and Intralesional Triamcinolone Acetonide.

Acne keloidalis nuchae is a chronic inflammatory condition affecting the occipital area or nape of the neck characterized by fibrotic papules, firm pustules, and nodules that coalesce into keloid like mass or plaques. It was first described by Kaposi in 1969. It is also known as lichen keloidalis nuchae, dermatitis papillaris capillitia, and folliculitis nuchae scleroticans. If not treated in the early stages of the disease it tends to be refractory to conventional methods like topical, intralesional steroids with antibiotics or retinoids. Surgical interventions remain the only choice in such cases. Various surgical modalities including surgical excision with primary or secondary closure, split-thickness skin grafts, and laser-assisted treatments have been tried. Most surgical methods have longer downtime with a higher chance of relapse. We studied the results of a combined treatment option carbon dioxide laser ablation followed by intralesional triamcinolone injection in the same sitting. This outpatient procedure has shown good results with no relapse and less downtime.

Effectiveness of Water-Amine Combined Process for CO2 Extraction from Biogas

Abstract The EU countries are implementing biomethane production projects from biogas, supplying it to the natural gas distribution grid, or using it as motor fuel. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression. Biogas production from landfills, agriculture waste, and sewage is already implemented in Ukraine, so the next step must be biomethane production on an industrial scale and the selection of biogas separation technology is important. Using 11 years of industrial experience in biogas production from landfills, wide experience of the different methane-containing gases separations, and small companies’ industrial possibilities, the most applicable separation technologies for Ukraine were selected: amine, water, and combined water amine carbon dioxide separation. These technologies had compared using computer simulation with real landfill biogas flow rate debt. Results of a software simulation of the most applicable water-amine absorption technology were verified using a laboratory setup. For carbon dioxide concentration in biogas at 32–42 % vol., the specific energy consumption when using water absorption is on average 2 times less compared to amine absorption, but at the same time, the loss of methane due to its solubility in water during water absorption amounted to 7.1–7.6 %, with practically no losses in amine absorption, and minor losses at 0.17–2.8 % in combined water-amine technology. The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for the regeneration process of saturated amine absorbent, as part of carbon dioxide has already been removed with water technology; b) using the methane excess to compensate power consumption of the biogas compressor during the preliminary water absorption of carbon dioxide and/or to compensate heat costs of the saturated amine absorbent regeneration

Compressed fluid-based technology for downstream isolation of bluish anthocyanin-derived pigments obtained from blueberry surplus.

A dynamic compressed fluid-based separation process combining carbon dioxide and ethanol was explored to isolate portisins previously hemi-synthesized from blueberry surplus anthocyanins. The influence of process parameters such as pressure (100-500 bar), temperature (40-60 °C), and ethanol content in the compressed fluid mixture (20-50 wt%) on extraction yield, portisins yield, and portisins content in the extract was investigated. The two-step isolation process includes (1) a first step at 100 bar, 60 °C, and 20 wt% ethanol content in the compressed fluid mixture to remove the low polarity compounds; and (2) a second step at 500 bar, 40 °C, and 100 wt% ethanol to recover portisins, resulting in a 1.5-fold increase in portisins content. The performance of the two-step separation process was compared to centrifugal partitional chromatography and conventional reverse phase liquid chromatography already reported in terms of portisins content in the extract, process throughput, process efficiency, and total solvent used. The two-step separation process decreased the total solvent used, although with a decrease in the throughput and efficiency. Nevertheless, the choice of the best separation technology depends on the application, as these techniques result in different portisins purities. Overall, this study contributed to a scalable and more sustainable process for natural colorant production, specifically focusing on blue pigments, with several industrial applications.

Deep pore grafting modification for PVDF membrane by supercritical carbon dioxide in combination with ultraviolet irradiation to improve permselectivity and oil/water separation performance

In order to enhance PVDF membrane’s permselectivity to oil and water during oil-water separation process, an efficient strategy that combining supercritical carbon dioxide technology (scCO2) and ultraviolet (UV) irradiation was proposed to change the wettability of PVDF membrane. The grafting of -COOH groups on PVDF membrane surface was demonstrated by FTIR-ATR, XPS and SEM. Deep pore grafting of acrylic acid in membrane pore interior was confirmed by establishing force models and corresponding wettability test. The results showed that permeate flux of deep pore modified membrane was 69.64Lm-2 h-1, which was 17.23% and 7.44% higher than that of unmodified membrane and surface modified membrane respectively. Interestingly, when reaction temperature not reached 40℃, some modified membranes were impermeable to water although they had good surface hydrophilicity, which was closely related to the critical point state of supercritical fluid mixture system.

Modeling Long-Term Facilitation of Respiration During Interval Exercise in Humans

Long-term facilitation (LTF) of respiration has been mainly initiated by intermittent hypoxia and resultant chemoreceptor stimulation in humans. Comparable levels of chemoreceptor stimulation can occur in combined exercise and carbon dioxide (CO2) inhalation and lead to LTF. This possibility was supported by data collected during combined interval exercise and 3% inhaled CO2 in seven normal subjects. These data were further analyzed based on the dynamics involved using mathematical models in this study. Previously estimated peripheral chemoreceptor sensitivity during light exercise (40 W) with air or 3% inhaled CO2 approximately doubled resting sensitivity. Ventilation after a delay increased by 17.0 ± 2.48 L/min (p < 0.001) during recovery following 45% maximal oxygen uptake (VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$V_{{{\ ext{O}}_{2} \\max }}$$\\end{document}) exercise consistent with LTF which exceeded what can be achieved with intermittent hypoxia. Model fitting of the dynamic responses was used to separate neural from chemoreceptor-mediated CO2 responses. Exercise of 45% VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$V_{{{\ ext{O}}_{2} \\max }}$$\\end{document} was followed by ventilation augmentation following initial recovery. Augmentation of LTF developed slowly according to second-order dynamics in accordance with plasticity involving a balance between self-excitatory and self-inhibitory neuronal pools.

Soil carbon plays a role in the climate impact of diet and its mitigation: the Finnish case

IntroductionDiet has a significant impact on the consumer’s climate impact, and a radical global change in the food system is necessary. However, the change needs to be interpreted and adapted to local conditions.MethodsTo support national climate policy, we evaluated current Finnish diet and its four alternatives: “current diet”; “meat to half diet”; “meat to a third diet”; “a diet rich in fish and milk”; and “a vegan diet”. We created the FoodMin model to simultaneously address both climate impacts and nutrient uptake and to combine carbon dioxide (CO2) emissions from soil organic matter (SOM) degradation with dietary climate impact assessments. As a well-established assessment method remains lacking, product group-specific estimates for the CO2 emissions of SOM origin were produced in two different ways, based on long-term observational data or by modelling with the Yasso07. We also examined, using three scenarios, how much the achievement of soil carbon (C) balance in Finnish production could affect the climate impact of the diet.Results and DiscussionThe climate impact of the current diet was 6.0 kg CO2 per person per day, and for alternative diets, the change compared with the current diet was −14%, −20%, −31%, and −39% respectively, for “meat to half” (5.2 kg CO2 eq. per person per day), “meat to third” (4.8), “a diet rich in fish and milk” (4.2), and “the vegan diet” (3.7). SOM-derived CO2 emissions from domestic fields accounted for 18% of the climate impact of the current diet and up to 23% of alternative diets. In terms of the soil C-balance scenarios, all actions together could mean a 3–13% reduction in the climate impact of the diet: the more products of animal origin, the more reduction opportunities in the diet. With the change in diet, these measures could reduce the climate impact of diets by 13–41%. The nutritional value of a “diet rich in fish and milk” was the best. The study revealed that SOM-induced CO2 emissions and SOM-related activities play a very important role in the climate impact of the diet and its mitigation; they cannot be ignored in dietary assessments in addition to direct product choices.

Performance comparison of organic Rankine cycles integrated with solar based combined cycle: A thermodynamic and exergoenvironmental analysis

In the present study, the two configurations of the combined intercooled cascade supercritical carbon dioxide (sCO2) cycle/organic Rankine cycle (ORC) (configuration-1) and the combined intercooled cascade sCO2 cycle/parallel double evaporator ORC (PDORC) (configuration-2) were considered for the comparison on the basis of thermodynamic performance. Solar power tower (SPT) was considered as heat source for both the configurations. The effects of SPT design parameters on the systems were investigated. It was concluded that the addition of basic ORC and PDORC to the standalone intercooled cascade sCO2 cycle enhanced the thermal efficiency by 2.26% and 6.66% respectively, at 950 W/m2 of direct normal irradiation (DNI). In the case of basic ORC and PDORC, the waste heat recovery ratios were 0.1197 and 0.1775, respectively. It was also discovered that configuration-2 performed better than configuration-1 in terms of waste heat recovery and its optimized thermal efficiency was found as 52.34%. An exergoenvironmental analysis also performed on the present systems. Exergoenvironmental impact index decreases from 1.6504 to 0.6801 with increase in DNI while the exergetic stability factor increase from 0.3773 to 0.5952 with DNI.

Use of A-Site Metal Exsolution from a Hydrated Perovskite Titanate for Combined Steam and CO2 Reforming of Methane.

Metal segregation from a perovskite oxide (ABO3) usually referring to "redox metal exsolution" has recently been used for in situ preparation of a well-designed catalyst where metal nanoparticles are homogeneously and strongly embedded on perovskite scaffolds upon reduction. The exsolution concept of B-site transition metal ions has grown, but several issues such as segregation of A-site alkaline-earth metal ions (altering electronic structures of the perovskite surface, causing deformation of perovskite structures, or creating undesirable products via side reactions) and carbon formations on metal nanoparticles should be addressed for stable catalysts in greenhouse gas (CO2 or CH4) conversion. Here, we suggest a new approach to designing metal-perovskite composite catalysts via A-site metal segregation from a hydrated perovskite titanate. In situ formation of A-site-deficient hydrated CaTiO3 accompanied with Ni exsolution solids leads to ∼78 and 65% of CH4 and CO2 conversion, respectively, suppressing carbon formations and alkaline-earth metal segregations in combined steam and carbon dioxide reforming of methane at 700 °C. It would help to design active and stable metal-perovskite catalysts for energy and environmental applications.

Alternating direction of catholyte forced flow-through 3D-electrodes improves start-up time in microbial electrosynthesis at applied high current density

Microbial electrosynthesis is an uprising concept for the combined carbon dioxide reduction and electricity storage in the form of green chemical compounds. Although several proof of principle studies show great promise, mass-transfer limitations of substrates, protons and products remains one of the issues that needs to be addressed to bring the systems towards greater scale applications. A previously tested solution formed force flow-through catholyte recirculation, but this set-up encountered difficulties with gas accumulation during start-up at higher current densities (∼ −10 kA/m3), creating the need for a bypass to release gas. In this study, start-up at high current density was achieved without a bypass by using an alternating flow-through regime. This regime decreased the operating energy input from 221 to 136 kWh per kg of produced hydrogen and reached acetate production within 10 days after start-up at high current density and elongation to n-caproate after 45 days. Mass-transfer studies were included by microsensor measurements of local conditions (hydrogen concentration, pH) combined with thermodynamic calculations at the start and end of 60-days biotic experiments. The microorganisms on the cathode decreased pH gradients and consumed the formed hydrogen. The presence of Clostridium sensu stricto 12 and Peptococcaceae species were related to chain elongation activity, and the presence of Methanobrevibacter was linked to methanogenesis activity. By identifying the effects of different flow-through strategies on local concentrations and functional microbial groups, this work provides insights on the optimal conditions for microbial CO2 conversion and highlight the application potential of microbial electrosynthesis.

The use of carbon dioxide and intense pulsed light laser for the treatment of hypertrophic burn scars: A case series.

Hypertrophic scarring is a common and debilitating consequence of burn scars. While there is limited evidence for current treatment options, laser therapy has been shown to be effective, low risk and minimally invasive. This study assesses the use of carbon dioxide lasers and intense pulsed light devices in the treatment of hypertrophic burn scars. In this case series, patients were recruited from a hypertrophic burn scar waitlist and completed a Patient and Observer Scar Assessment Scale prior to and six weeks after laser therapy. The Nordlys (intense pulsed light) and CO2RE (carbon dioxide) systems from Candela Medical were used, with a range of settings used depending on the assessment of the burn scar. The differences between scores were calculated for the total Patient and Observer Scar Assessment Scale score, pain, itch, colour, stiffness, thickness, irregularity and the overall opinion of the scar. Statistical analysis was completed using a paired, two-tailed student T test. A total of 31 patients were recruited for this trial with a range of scar locations, surface areas and mechanism of burn injury. The calculated difference in mean showed a significant reduction for the overall Patient and Observer Scar Assessment Scale score (1.93, p < 0.0001), pain (1.39, p = 0.0002), itch (1.84, p = 0.0002), colour (1.97, p < 0.0001), stiffness (2.47, p < 0.0001), thickness (2.1, p < 0.0001), irregularity (1.89, p < 0.0001) and overall opinion (1.58, p = 0.0003). Current management options for hypertrophic scarring have limited evidence. Laser therapy presents a minimally invasive procedure that can be completed under topical anaesthetic and has shown to be effective following a single treatment of combined carbon dioxide laser and intense pulsed light device therapy. Many people will suffer a burn injury throughout their life and up to almost 3 out of 4 people with burn injuries will suffer from hypertrophic scars (a thickened, red and itchy scar). These scars cause distress both due to their appearance and their reduction of function, particularly over a joint or muscle. Laser therapy, in which different wave lengths of light (pulsed light) or gas (carbon dioxide) target the scar, has been found to be effective and have minimal side effects in the management of hypertrophic scars. While individual lasers have been assessed and found to be effective and low risk, the combined use of multiple lasers on the same scar has not been extensively studied. We studied the effectiveness of both light and gas laser therapies on hypertrophic scars. Patients with hypertrophic scars completed a questionnaire that focused on their perspective of their scar (pain, itch, stiffness, thickness, irregularity, overall opinion) prior to the treatment. The patients then underwent laser therapy (with local anaesthetic gel) with either pulsed light and/or carbon dioxide (gas) laser. The type of laser used was decided by the clinician performing the therapy depending on scar location and thickness. Patients then re-completed the subjective survey six weeks following the laser therapy, and the results compared. We learnt that laser therapy (both light, gas and a combination of both) are effective (and low risk) in reducing the subjective burden of the scar for the patient.

Thermodynamic Performance Analysis of Combined Recompression Supercritical Carbon Dioxide (SCO2): Organic Rankine Cycle (ORC) for Waste Heat Recovery

An energy and exergy-based performance evaluation of combined recompression supercritical carbon dioxide Brayton cycle and organic Rankine cycle (SCO2/ORC) is presented. A parametric investigation has been performed by varying input parameters such as compressor outlet pressure , SCO2 turbine temperature , SCO2 mass flow rate , flow split fraction, LTR effectiveness and HTR effectiveness. R1234ze, R1234yf, and R245fa working fluids were considered in the bottoming cycle of SCO2/ORC. Results obtained revealed that the R1234ze-based SCO2/ORC system demonstrated the highest thermal and exergy efficiency of 55.87% and 73.13% respectively, at = 30MPa and = 3900C; 51.47% and 80.39% at = 3kg/s when the split fraction is between 0.357 and 0.4; 52.19% and 71.44% at = 0.95; and 52.19% and 71.44% at = 0.95. However, the R245fa-based SCO2/ORC system is observed to have the lowest thermal and exergy efficiency. The maximum exergy destruction is seen to occur in the gas heater with 36.97% (8.45kW) of input exergy destroyed in this component. It is followed by the recompression compressor at 17.17% (3.93kW) and the SCO2 turbine at 16.03% (3.67%), with the ORC pump at 0.157% (0.036kW) having the least exergy destroyed.

841 ASSOCIATION BETWEEN CARDIORESPIRATORY SYMPTOMS AND LUNG FUNCTION IN PATIENTS WITH LONG-COVID SIGNS

Abstract Background Many patients recovered from COVID-19 infection present a variety of symptoms which limits overall quality of life, as reduced exercise performance, dysfunctional breathing, cough, dyspnea, weakness and anxiety. This condition has been named long COVID. The origin of this symptomatology is still unclear. This study has the aim to analyse the relation between symptoms and respiratory function, focusing on the alveolar capillary membrane. Methods Consecutive patients with long COVID 19 symptoms after 6 months were included. Patients underwent full clinical evaluation, laboratory tests, echocardiography, thoracic CT scan, spirometry including alveolar capillary membrane diffusion by means of combined carbon dioxide and nitric oxide lung diffusion (DLCO/DLNO) and cardiopulmonary exercise test. We measured surfactant derive protein B (immature form) as blood marker of alveolar capillary function. A questionnaire allowed to evaluate symptoms. Results We evaluated 204 post COVID-19 patients (age 56.5±14.5 y, 89 females (44%), BMI 25.7±4.0, 6% active smokers) referring to our hospital 171±85 days after the end of acute COVID-19 infection (Fig. 1). None of spirometry data was associated with long COVID 19 referred symptoms. SPB was not associated to differences in any of the referred symptoms. Subjects with lower capillary volume (VCap) have more frequently dyspnea, tiredness, fatigability and hair loss (Fig.2). CT scan lung damage correlated with SPB and membrane diffusion but not with VCap, exercise performance or VE/VCO2 slope. The strongest correlation of SPB were with lung parenchyma damage and Vcap. Conclusions Our data suggest that a relevant reduction of alveolar capillary membrane function plays a central role in the long COVID cardiorespiratory symptoms.