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Introduction : Umbilical access in laparoscopic surgery has been cited as a factor for increased complications in low-birth-weight infants and those less than three months old. In a previous series, 10.6% of pediatric surgeons reported complications in this population associated with umbilical access, citing carbon dioxide (CO2) embolism as the most common complication. To further examine the safety of this technique, we report our outcomes with blunt transumbilical laparoscopic access at our institution over four years. Methods : A retrospective review was performed of patients less than three months of age who underwent laparoscopic pyloromyotomy or inguinal hernia repair from 2016-2019. Operative reports, anesthesia records, and postoperative documentation were reviewed for complications related to umbilical access. Complications included bowel injury, vascular injury, umbilical vein cannulation, CO2 embolism, umbilical surgical site infection (SSI), umbilical hernia requiring repair, and death. Results : Of 365 patients, 246 underwent laparoscopic pyloromyotomy, and 119 underwent laparoscopic inguinal hernia repairs. Median age at operation was 5.9 weeks [4.3,8.8], and median weight was 3.9 kg [3.4,4.6]. Nine complications (2.5%) occurred: 5 umbilical SSIs (1.4%), 1 bowel injury upon entry requiring laparoscopic repair (0.2%), 1 incisional hernia repair 22 days postoperatively (0.2%), and 2 cases of hypotension and bradycardia upon insufflation that resolved with desufflation (0.5%). There were no intraoperative mortalities or signs/symptoms of CO2 embolism. Conclusion : In this series, umbilical access for laparoscopic surgery in neonates less than three months of age was safe, with minimal complications. Although concern for umbilical vessel injury, cannulation, and CO2 embolism exists, these complications are not exclusively associated with umbilical access technique.

Introduction Transoral laser microsurgery represents the treatment of choice for early glottic cancer. Its use and effectiveness are mainly related to laryngeal exposure and deep extension of tumor. Histopathologic assessment of surgical margin presents a main issue about transoral laser microsurgery and complete oncological excision. Objective The aim was to analyze the impact of revision surgery on organ preservation and local disease control in patients with early glottic cancer treated by transoral laser microsurgery. Methods We carried out a retrospective study on a cohort of 153 patients with early glottic cancer (Tis, T1, T2) treated by transoral laser microsurgery. Resection margins were classified as follows: “free” if macroscopic margin-tumor distance was at least 2 mm, as “close” if it was less than 2 mm and “positive” if the margin was involved by carcinoma. Patients were divided into two groups: patients with free resection margins (Group A) and patients with positive, close or not-evaluable resection margins (Group B). Group A (36) underwent periodic followup. Group B (117) underwent a second look laser CO2 2 months after surgery. Fifteen patients of Group A with suspected persistence of carcinoma during followup underwent a second laser resection after a time interval of 4–8 months after first surgery. Overall survival, disease-free survival, disease-specific survival, ultimate local control with laser alone and organ preservation rates were estimated. Results Five-year overall survival rate and 5-year disease-specific survival were 100% in both groups. The five-year laryngeal preservation rate was 100% in Group A and 95.2% in Group B. Five-year disease-free survival was 92.15% and 5-year ultimate local control with laser alone in 92.15% of patients. Conclusion This study has demonstrated that revision Transoral Laser Microsurgery is able to confirm the oncological radicality in most cases, even in the case of positive, close or non-evaluable margins. Considering our results, according to our experience, the second look with CO2 laser is a therapeutic strategy to consider, even in the case of close or non-evaluable as well as positive margins.

A 46-year-old man experienced facial burns due to a fire in his house. In the prehospital setting, suspecting inhalation injury and carbon monoxide poisoning, an emergency physician decided to bring him to the hospital for carbon dioxide (CO2) monitoring without endotracheal intubation for approximately 20 min because of less severe respiratory distress. On the way to the hospital, the patient’s end-tidal CO2 monitoring ranged from 19 to 30 mm Hg, and transcutaneous carbon dioxide (TcPCO2) remained between 50 and 55 mm Hg. On arrival at the hospital, PaCO2 showed 51.6 mm Hg. Endotracheal intubation using a bronchoscope was performed in the emergency room, and inhalation injury was observed. He was extubated on day 5 and discharged on day 10. In the prehospital setting, TcPCO2 monitoring is useful for initial management of non-intubated inhalation injury patients even with high concentration oxygen.

Iraq is located on the northeastern parts of the Arabian Plate, which has been particularly exposed to tectonic movements in past geological periods, where there are several giant fields that contain most of the country’s oil reserves. The structural features of the oil fields of southern Iraq (Mishrif and Zubeir) form a number of factors that complicate the construction and operation of wells for oil production in the region.Possible negative consequences of the corrosion processes of oil and gas equipment and the prospective use of new technologies and materials were considered, taking into account the fact that waterflooding is currently the main technology in oil production in Iraq, which in these conditions requires a large amount of water and carries a number of negative factors that complicate operation of oil production equipment.These main factors are the content of acid gases (hydrogen sulfide and carbon dioxide), high mineralization of formation water, mainly due to the presence of chloride ions, elevated temperature, which is due to the depth of drilling and well operation. The negative consequences of corrosion of oil and gas equipment are given. The study was based on an integrated approach, which was carried out by analyzing data on the formation of geological conditions in southern Iraq (tectonics, stratigraphy, lithological-facial and hydrological analysis), generalization of world experience in oil production, use of oil and gas resources.

Supplement to the depleting energy resources and the stringent environmental laws regarding the atmospheric emissions of greenhouse gases, the development of clean and renewable sources of energy has been a great issue. Worldwide, energy usage is steadily increasing and would continue to increase in the coming years; the effects of global warming are also becoming more and more prevalent. Biogas holds a promising future in the sustainable supply of low-cost energy that will minimize greenhouse gas emissions. Unlike solar and wind, biogas does not rely on weather conditions. It can also be stored and transported making it easily adaptable to changes in demand. This study would utilize membrane technology for the upgrading of biogas to a clean and useful fuel replacing fossil fuels and consider the limiting factors of the process found in literature which is the trade-off between gas permeability and selectivity. In doing so, we analyse the factors that affect permeability and selectivity of ceramic membranes and then introduce methods of optimisation. Biogas components are passed through the membrane as feed gas to observe the flow characteristics at various operating conditions for membranes with different pore sizes. It was observed that for all pore sizes studied, there was a proportional rise in flowrate as the feed pressure was increased from 0.2 to 3 bar. Also, an increase in temperature from 20 °C to 100 °C favoured the membrane selectivity. In general, methane gas showed a higher flux than carbon dioxide irrespective of the operating conditions indicating that the permeation of the gases is related to their molecular weight, for example, using 15 nm membrane at 20 °C and 3 bar, a flux of 3.59 and 2.27 L/min was obtained for CH4 and CO2 respectively with the same trend recorded using other pore sizes, temperature and pressure ranges. It must also be noted that the pore size plays a vital role in the optimisation of membrane process as the 15 nm membrane, being the lowest mean pore size studied showed the highest separation factor of 1.60 which is close to the ideal Knudsen value. Overall, it was found that the behaviour of gases through these membranes is determined by an interplay of factors – dynamic size and diffusion rate.

Electrical and electromagnetic (EM) techniques are used to map the electrical resistivity of the subsurface. The injection of carbon dioxide (CO2) is likely to form a lenticular, slab or wedge-like...

The purpose of this paper is to investigate the links between renewable energy (RE), non-renewable energy (NRE), capital, labour and economic growth, using the Non-linear Auto Regressive Distributive Lag (NARDL) model in Malaysia for the period of 1980–2018. The results of NARDL confirm the asymmetric effect of RE and NRE consumption on the economic growth in the long run as well as short run in Malaysia. The findings also show that in the long and short-run, positive shocks of NRE are greater than the positive shocks of RE. It indicates that Malaysia's economic growth is highly dependent on NRE which is not a good indication as NRE consumption increases carbon dioxide (CO2) emission in the country. Moreover, the empirical results of this study demonstrated that RE consumption reduction accelerates economic growth whereas NRE consumption reduction decreases economic growth. It can have claimed that in Malaysia RE is still more expensive than NRE. In conclusion, this study offered a variety of measures to develop RE to reduce the dependency on NRE consumption.

Environmental sustainability and climate change mitigation seem central in the fight against global warming and continuous human sustenance in the twenty-first century. However, non-renewable and renewable energy are at the core of these pollution concerns, particularly among the G20 economies that are the top pollution emitters. Capital investment has been argued to ameliorate or amplify the relationship, unlike other mediators in the energy-pollution nexus. To this end, the study specifically sets out to unravel the mediating role of capital investment in energy-pollution link together with other pollution confounders, including trade openness, foreign direct investment, and energy use for G20 economies over the period 1990-2017. We report vital findings using the pooled mean group estimator and accounting for cross-sectional dependence and heterogeneity among the countries. First, results show that renewable energy negatively impacts carbon emissions in both the short and long runs, while non-renewable energy positively impacts pollution. In addition, the results show that capital investment lowers pollution in the short run but increases it in the long run. Lastly, on interacting capital investment with renewable energy, we find that pollution falls in both the short and long runs, while its interaction with non-renewable energy expands pollution in both periods. On the policy front, since capital investment provides an important channel to reduce pollution in G20 nations, it is therefore recommended that if energy consumption is to work through the capital investment channel to lower pollution in the G20, the proportion of renewable energy must increase relative to non-renewable energy in their energy mix.

The current energy crisis and the escalating concern over pollution level necessitate the development of various low emission and clean technologies for efficient utilization of fossil fuels. These technologies offer the benefits of using fossil fuels continuously without harming the environment. Oxy fuel combustion technology is one of the promising low emission combustion technologies having an additional advantage of being a better retrofit option compared to other clean technologies. In the present study, the stability and flame characteristics of LPG flame in a tubular burner has been investigated with oxygen as the oxidizing gas and nitrogen or carbon dioxide as the balance gas. The experiments were conducted to study the effect of primary aeration and the effect of balance gas on the stability and flame characteristics of air and oxy flames. The experimental results from the preliminary experiments show that the flame height decreases with increase in primary aeration for both air and oxy cases and the premixed blue zone increases with primary aeration. The flames observed for oxy cases are dull and weak at all equivalence ratio (or primary aeration). The measured axial flame temperature indicated that the temperature of oxy flames is lower than that of the air flames for the same primary aeration. The data obtained from the stability tests show that the oxy flames can withstand relatively lower port velocity than its air counterpart. Therefore, the stable operating range of the given burner design is lower when CO2 is used as the balance gas. These differences in the stability and flame characteristics is attributed to the difference in the thermo physical properties like molar heat capacity, mass diffusivity and thermal conductivity of the balance gas CO2 and N2.

Objective To investigate the safety and effectiveness of extraluminal placement of a bronchial blocker compared with carbon dioxide (CO2) artificial pneumothorax in infants undergoing video-assisted thoracoscopic surgery (VATS). Methods The study involved 33 infants (group A) who underwent one-lung ventilation (OLV) with extraluminal placement of a bronchial blocker and 35 other infants (group B) who underwent CO2 artificial pneumothorax. Clinical characteristics, the degree of lung collapse, and complications were compared. Results The degree of lung collapse in group A was significantly higher than that in group B at T2 and T3. The mean arterial pressure (MAP) of group B was significantly lower than that of group A at 10 min and 30 min after OLV. The partial pressure of carbon dioxide (PaCO2) of group B was significantly higher than that of group A at 30 min after OLV. The incidence of hypotension in group B was higher than that in group A. Conclusion Compared with CO2 artificial pneumothorax, extraluminal placement of a bronchial blocker is associated with a better degree of lung collapse, fewer episodes of hypotension, and lower PaCO2 accumulation during OLV in infants undergoing VATS.

The deep tillage of soil consumes fuel at higher costs, which creates a large amount of carbon emissions. For large-scale farming in particular, the threat to the environment cannot be ignored. Currently, very few studies have considered the impact of the size of the deep tillage area on carbon emissions. Effectively controlling the size of the deep tillage area can reduce the emission of carbon dioxide at a certain level and optimize profits, which is crucial to the sustainable development of agricultural supply chains. In this paper, we design a new contract-farming rice supply chain network based on “Cooperative + Storage Company”, which considers tillage as the start point for the supply chain echelon. A multi-product, multi-period, bi-objective optimization model is proposed to maximize profit and minimize carbon emissions in the network. Moreover, we consider the grain rotation task of the storage company in the modeling. The L p -metrics method is used to solve the bi-objective model. Subsequently, an actual scenario is used to verify the effectiveness of the model. The results indicate that changes in the size of the deep tillage area have a significant impact on carbon emissions, and the size of the deep tillage area is negatively correlated with the total farm size, thereby affecting the carbon dioxide release. The results also indicate that carbon emissions can be minimized by increasing the number of cooperatives or expanding the size of farms. The proposed model can aid decision-makers in selecting an optimal set of solutions based on their preferences or policies.

The prevalence of sleep-disordered breathing (SDB) is higher in older adults compared with younger individuals. The increased propensity for ventilatory control instability in older adults may contribute to the increased prevalence of central apneas. Reductions in the cerebral vascular response to CO(2) may exacerbate ventilatory overshoots and undershoots during sleep. Thus, we hypothesized that hypercapnia-induced cerebral vasodilation (HCVD) will be reduced in older compared with younger adults. In 11 older and 10 younger adults with SDB, blood flow velocity in the middle cerebral artery (MCAV) was measured using Doppler transcranial ultrasonography during multiple steady-state hyperoxic hypercapnic breathing trials while awake, interspersed with room air breathing. Changes in ventilation, MCAV, and mean arterial pressure (MAP) via finger plethysmography during the trials were compared with baseline eupneic values. For each hyperoxic hypercapnic trial, the change (Δ) in MCAV for a corresponding change in end-tidal CO(2) and the HCVD or the change in cerebral vascular conductance (MCAV divided by MAP) for a corresponding change in end-tidal CO(2) was determined. The hypercapnic ventilatory response was similar between the age groups, as was ΔMCAV/Δ [Formula: see text]. However, compared with young, older adults had a significantly smaller HCVD (1.3 ± 0.7 vs. 2.1 ± 0.6 units/mmHg, P = 0.004). Multivariable analyses demonstrated that age and nadir oxygen saturation during nocturnal polysomnography were significant predictors of HCVD. Thus, our data indicate that older age and SDB-related hypoxia are associated with diminished HCVD. We hypothesize that this impairment in vascular function may contribute to breathing instability during sleep in these individuals. NEW & NOTEWORTHY This study demonstrates, for the first time, in individuals with sleep-disordered breathing (SDB) that aging is associated with decreased hypercapnia-induced cerebral vasodilation (HCVD). In addition to advanced age, the magnitude of nocturnal oxygen desaturation due to SDB is an equal independent predictor of HCVD.

This work investigates the possibility of estimating the seasonal variation of global carbon dioxide (CO₂) from the data procured by Orbiting Carbon Observatory-3 (OCO-3) during the global lockdown related to the novel coronavirus (COVID-19) pandemic. A comparative analysis with the National Aeronautics and Space Administration's (NASA's) Orbiting Carbon Observatory-2 (OCO-2) is carried out using the time series data on column-averaged dry air CO₂mole fraction (xCO₂) and solar-induced fluorescence (SIF), a parameter pertinent to CO₂, for nine crowded urban places and nine unpopulated places with negligible human activity, each of 2°x 2°area selected randomly from different global locations. The resulting similarities and dissimilarities in the trends of the seasonal variations of xCO₂and SIF give clear indication of a reduction in the CO₂column average, especially in the crowded urban regions, which experienced restricted fossil fuel burning situation during the global COVID-19 pandemic in year 2020. A wavelet coherence technique is suggested for quantifying the temporary reduction using the OCO-2 data recorded in years 2018-2020 as reference. This methodology is hoped to be useful in future comparison of OCO-3 with its own annual data. IEEE

BACKGROUND: Minute ventilation/carbon dioxide production (VI‡E/VI‡CO2) is a variable of cardiopulmonary exercise testing (CPET), which is evaluated by arterial CO2pressure and ventilation-perfusion mismatch via invasive methods. This study evaluated substitute non-invasively obtained variables for minimum VI‡E/VI‡CO2(Min) and VI‡E vs. VI‡CO2slope (Slope) and the relationship between Min and Slope.Methods and Results:This study enrolled 1,052 patients with heart disease who underwent CPET and impedance cardiography simultaneously. At first, the correlations between the end-tidal CO2pressure (PETCO2), tidal volume/respiratory rate (TV/RR) ratio, VI‡E and VI‡CO2Y-intercept (Y-int), and cardiac index (CI) and the Min and Slope were investigated. Second, the correlation between Min and Slope was investigated. PETCO2showed the largest correlation value among the 4 variables. These 4 variables could reveal 84.2% and 81.9% of Min and Slope, respectively. Although Slope correlated with Min (R=0.868) and predicted 78.9% of Min, considering these 4 variables, Slope+Y-int was more strongly correlated with Min (R=0.940); the Slope+Y-int revealed 90.6% of the Min relationship in the multiple regression analysis. CONCLUSIONS: Over 80% of the Min and Slope values were revealed with the above-mentioned 4 variables collected non-invasively. The formula, Min∝Slope+Y-int, can reveal >90% of the Min/Slope relationships, and the Y-int may be a crucial factor to clarify the relationship between Min and Slope.

Background: Recent advancements in the context of shock pathophysiology, support ultrasound assessment of organ perfusion. Renal resistive index (RRI) has been used to evaluate renal blood flow. Our aim was to investigate the relation between RRI, and global tissue hypoperfusion indices, in mechanically ventilated critically ill patients and their association with clinical outcome.Methods: In this prospective observational study, RRI was measured within 24 hours of intensive care unit (ICU) admission. Clinical and laboratory data, routine hemodynamic variables and gas exchange at the time of RRI assessment were recorded. The ratio of central venous-to-arterial carbon dioxide partial pressure difference by arterial-to-central venous oxygen content difference (P(cv-a)CO2/C(a-cv)O2) and lactate were used as global tissue hypoperfusion indices. Results A total of 126 mechanically ventilated patients were included [median age 61 (IQR 28) years, 74% males]. Seventy-seven patients had RRI values >0.7. P(cv-a)CO2/C(a-cv)O2 ratio and arterial lactate, were significantly higher in patients with RRI > 0.7 compared to those with RRI ≤0.7 [2.4 (2.2) versus 1.2 (0.6) and 2.88 (3.39) versus 0.62 (0.57) mmol/l respectively, both p(cv-a)CO2/C(a-cv)O2 ratio and arterial lactate for the whole patient population (rho=0.64, both p2 / C(a-cv)O2 ratio [3.67 (3.8) versus 0.91 (1.4)] and lactate levels [2.80 (2.00) versus 1.50 (1.20)], both p (cv-a)CO2/C(a-cv)O2 ratio with clinical outcome. RRI showed good ability to predict ICU mortality (AUC 74.9% (95% CI 61% - 88.8%). The combination of RRI with P(cv-a)CO2)/(C(a-cv)O2 ratio and lactate better predicted mortality than RRI alone [AUC 84.8% (95% CI 5.1% - 94.4%)] versus 0.74.9%, respectively, pConclusions: In mechanically ventilated patients, renal blood flow impairment, assessed by the RRI on ICU admission, correlates with global tissue hypoperfusion indices. In addition, RRI in combination with tissue perfusion estimation is more valuable in predicting clinical outcome than RRI alone.

In the face of unrelenting climate change and insufficient mitigation, experts are increasingly considering using geoengineering - carbon dioxide removal and solar radiation management - to manipulate the Earth's climate. So far, most laypeople are unaware of geoengineering, and many are resistant to these technologies when told about them. A growing literature finds that these initial reactions are tied to psychological traits, beliefs, and identities including trust in the actors involved, political and social identities, beliefs about tampering with the natural world, and perceived trade-offs between geoengineering and alternative approaches. Finally, given the lack of existing knowledge of geoengineering, public acceptance is highly susceptible to how these technologies are framed, offering both risks and opportunities for climate communication.

The purpose of this case study and review was to understand the perianesthestic care of paradoxical air embolism (PAE) in patients undergoing hysteroscopic surgery. The perianesthestic management record of a patient undergoing hysteroscopic surgery was analyzed to study the characteristics of PAE, and the literature describing the perianesthestic care for PAE was reviewed. The first symptom of PAE in hysteroscopic surgery is often a decrease in end-tidal carbon dioxide (ETCO2), and the complications include embolism of the pulmonary artery, coronary artery, and cerebral artery. The best monitoring method is continuous ETCO2 monitoring, and intraoperative echocardiography is an excellent method to diagnose and guide the treatment of PAE. PAE is a rare but serious complication of hysteroscopic surgery that is associated with organ ischemia and hypoxia. Prevention and treatment of PAE requires the vigilance and cooperation of not only perianesthesia nurses and anesthesiologists but also the surgeons and operating room nurses. Early prevention, proper monitoring, and effective treatment are the keys to successful rescue for PAE.

Introduction: Evidence suggests the high capability of non-invasive assessment of the End-tidal carbondioxide (ETCO2) in predicting changes in arterial carbon dioxide pressure (PCO2) following major surgeries in children. We aimed to compare EtCO2 values measured by capnography with mainstream device and EtCO2 values assessed by arterial blood gas analysis before and after cardiopulmonary bypass pumping in cyanotic children. Methods: This cross-sectional study was performed on 32 children aged less than 12 years with ASA II suffering cyanotic heart diseases and undergoing elective cardiopulmonary bypass pumping. Arterial blood sample was prepared through arterial line before and after pumping and arterial blood gas (ABG)was analyzed. Simultaneously, the value of EtCO2 was measured by capnography with mainstream device. Results: A significant direct relationship was found between the changes in ETCO2 and arterialPCO2 (r = 0.529, P = 0.029) postoperatively. According to significant linear association between postoperative change in ETCO2 and arterial PCO2, we revealed a new linear formula between the two indices: ΔPCO2 = 0.89× ETCO2-0.54. The association between arterial PCO2 and ETCO2 remained significant adjusted for gender, age, and body weight. Conclusion: the value of ETCO2 can reliability estimate postoperative changes in arterial PCO2 in cyanotic children undergoing cardiopulmonary bypass pumping.

Blood oxygenation level-dependent (BOLD) or arterial spin labeling (ASL) MRI with hypercapnic stimuli allow for measuring cerebrovascular reactivity (CVR). Hypercapnic stimuli are also employed in calibrated BOLD functional MRI for quantifying neuronally-evoked changes in cerebral oxygen metabolism (CMRO2). It is often assumed that hypercapnic stimuli (with or without hyperoxia) are iso-metabolic; increasing arterial CO2 or O2 does not affect CMRO2. We evaluated the null hypothesis that two common hypercapnic stimuli, ‘CO2 in air’ and carbogen, are iso-metabolic. TRUST and ASL MRI were used to measure the cerebral venous oxygenation and cerebral blood flow (CBF), from which the oxygen extraction fraction (OEF) and CMRO2 were calculated for room-air, ‘CO2 in air’ and carbogen. As expected, CBF significantly increased (9.9% ± 9.3% and 12.1% ± 8.8% for ‘CO2 in air’ and carbogen, respectively). CMRO2 decreased for ‘CO2 in air’ (−13.4% ± 13.0%, p 2 during carbogen did not significantly change. Our findings indicate that ‘CO2 in air’ is not iso-metabolic, while carbogen appears to elicit a mixed effect; the CMRO2 reduction during hypercapnia is mitigated when including hyperoxia. These findings can be important for interpreting measurements using hypercapnic or hypercapnic-hyperoxic (carbogen) stimuli.

Rationale: Acute hypercapnic respiratory failure has been shown to be associated with worse outcomes for various disease states, but less is known about patients with compensated hypercapnic respir...

Background In middle-aged adults with depression, cerebral vasodilatory reactivity is blunted; however, this has not been examined in treatment-naive young adults with major depressive disorder (MDD). We tested the hypothesis that cerebrovascular reactivity would be blunted in young adults (18–30 yrs) with MDD compared to healthy non-depressed adults (HA) and would be attenuated to a greater extent in adults with symptomatic MDD (sMDD) compared to adults with MDD in remission (euthymic MDD; eMDD). Methods Sixteen adults with MDD [21±3yrs; n = 8 sMDD (6 women); n = 8 eMDD (5 women)] and 14 HA (22±3yrs; 9 women) participated. End-tidal carbon dioxide concentration (PETCO2; capnograph), beat-to-beat mean arterial pressure (MAP; finger photoplethysmography), middle cerebral artery blood velocity (MCAv; transcranial Doppler ultrasound), and internal carotid artery (ICA) diameter and blood velocity (Doppler ultrasound) were continuously measured during baseline and rebreathing-induced hypercapnia. Cerebrovascular reactivity was calculated as the relative increase in vascular conductance during hypercapnia. Results In adults with MDD, cerebrovascular reactivity in the MCA (∆39±9 HA vs. ∆31±13% MDD, p = 0.04), but not the ICA (∆36±24 HA vs. ∆34±18% MDD, p = 0.84), was blunted compared to HA. In the MCA, cerebrovascular reactivity was reduced in adults with sMDD compared to adults with eMDD (∆36±11 eMDD vs. ∆25±13% sMDD, p = 0.02). Limitations The cross-sectional nature approach limits conclusions regarding the temporal nature of this link. Conclusion These data indicate that MCA cerebrovascular reactivity is blunted in young adults with MDD and further modulated by current depressive symptomology, suggesting that the management of depressive symptomology may secondarily improve cerebrovascular health.

The global amount of energy contained in natural gas hydrates is huge, maybe as much as twice all known conventional fossil fuel sources. Unlike the worldwide distribution of conventional fossil fuels, hydrocarbons trapped in water as hydrate is also available in countries with limited conventional hydrocarbon sources. The development towards lower global emissions of greenhouse gases requires new strategies for the use of hydrocarbons, whether they are available as conventional sources, or in the form of natural gas hydrates. In this work we outline some possible strategies of utilizing hydrocarbon energy sources in a clean and environmentally friendly way. The use of carbon dioxide for producing hydrates is not new. Results from several experimental studies are available. In this work we shed more light on thermodynamic limitations and the need for additives in order to make the approach technically efficient. Through thermodynamic analysis we show that up to 20 mol per cent N2 is feasible in a CO2/N2 injection gas based on ability to form a new hydrate with fee pore water and the released enthalpy needed to dissociate in situ CH4 hydrate. Surfactant is also needed in order to keep the injection gas front free of blocking hydrate films. Small alcohols like methanol and ethanol have surfactant properties. It is demonstrated that even 10 wt% ethanol in liquid pore water still makes it feasible to create a new hydrate from injection gas containing 20 mol per cent N2. Consequences of other components than CH4 in the hydrate are also discussed. And in practical cases with a well-defined source of CO2 it is also important to investigate impact of other components like for instance H2S on the stability of injection gas hydrate, as well as changes in enthalpy of hydrate formation. Another key element of this work is the conversion of produced hydrocarbons over to hydrogen and carbon dioxide using steam cracking. The technology for this is very old and in daily use.

Catalytic steam hydrogasification of coal is a direct method for methane production. Calcium looping concept is usually used in coal gasification process for in-situ carbon dioxide removal and heat supply. In this paper, a new process combining catalytic steam hydrogasification and calcium looping was proposed and investigated using a self designed instantaneously feeding reactor under high-temperature and pressurized conditions. The effects of operation conditions (including hydrogen concentration with a range of 0–50 vol%, gasification pressure with a range of 0.1–3.5 MPa, gasification temperature with a range of 700–800 °C, and gasification-calcination cycle number up to six) on the performance of the new process have been studied. The results show that: (i) increasing H2 concentration is beneficial to methane products; (ii) high temperature and low pressure are not conducive to methane production and carbon dioxide capture as well as the self-sustained heat supply in gasifier; (iii) the methane content and carbon conversion can be maintained at 30–40 vol% and 75–80% for the durability tests. According to the performance of gas products, 750 °C 3.5 MPa and Ca/C = 0.5 are suggested for the new process. In addition, the gasification reactivity can be affected by the Ca–K-Char interaction as indicated by the XRD, FT-IR and SEM-EDX analysis.

Objective The objective of this study was to assess whether the central venous-to-arterial carbon dioxide partial-pressure difference (ΔPCO2) and the ratio of the ΔPCO2 to the arterial-venous difference in oxygen content (ΔPCO2/Ca-vO2) predict postoperative complications (PC) after cardiac surgery. Design Prospective, observational, noninterventional study. Participants The study comprised 60 patients undergoing cardiac surgery with cardiopulmonary bypass. Interventions The primary endpoint was the occurrence of PC. Data were first analyzed in two groups based on the occurrence of PC. Then, receiver operating characteristic curves of the ΔPCO2 and the ΔPCO2/Ca-vO2 ratio were analyzed for the prediction of PC. Measurements and Main Results Among the study participants, 22 (36.7%) experienced PC. The death rate was 18.3%. The present study found that the ΔPCO2 and the ΔPCO2/Ca-vO2 ratio predicted the occurrence of PC with areas under the curve of 0.702 and 0.666, respectively. The best thresholds of these markers were 8.3 mmHg for the ΔPCO2 and 2.16 mmHg/mL for the ΔPCO2/Ca-vO2 ratio. A significant difference was found for these indicators between the groups with and without PC. The ΔPCO2 and the ΔPCO2/Ca-vO2 ratio were significantly correlated to EuroSCORE II, duration of aortic clamping, majority of prognostic scores the first two days postoperatively, and the lactate level. The ΔPCO2/Ca-vO2 ratio is predictive of hyperlactatemia >2 mmol/L, with an area under the curve of 0.787. Conclusion The ΔPCO2 and the ΔPCO2/Ca-vO2 ratio predict the occurrence of complications in cardiac surgery.

Volatile anesthetics are increasingly used for sedation in intensive care units. The most common administration system is AnaConDa-100 mL (ACD-100; Sedana Medical, Uppsala, Sweden), which reflects volatile anesthetics in open ventilation circuits. AnaConDa-50 mL (ACD-50) is a new device with half the volumetric dead space. Carbon dioxide (CO2) can be retained with both devices. We therefore compared the CO2 elimination and isoflurane reflection efficiency of both devices.A test lung constantly insufflated with CO2 was ventilated with a tidal volume of 500 mL at 10 breaths/min. End-tidal CO2 (EtCO2) partial pressure was measured using 3 different devices: a heat-and-moisture exchanger (HME, 35 mL), ACD-100, and ACD-50 under 4 different experimental conditions: ambient temperature pressure (ATP), body temperature pressure saturated (BTPS) conditions, BTPS with 0.4 Vol% isoflurane (ISO-0.4), and BTPS with 1.2 Vol% isoflurane. Fifty breaths were recorded at 3 time points (n = 150) for each device and each condition. To determine device dead space, we adjusted the tidal volume to maintain normocapnia (n = 3), for each device. Thereafter, we determined reflection efficiency by measuring isoflurane concentrations at infusion rates varying from 0.5 to 20 mL/h (n = 3), for each device.EtCO2 was consistently greater with ACD-100 than with ACD-50 and HME (ISO-0.4, mean ± standard deviations: ACD-100, 52.4 ± 0.8; ACD-50, 44.4 ± 0.8; HME, 40.1 ± 0.4 mm Hg; differences of means of EtCO2 [respective 95% confidence intervals]: ACD-100 - ACD-50, 8.0 [7.9-8.1] mm Hg, P.001; ACD-100 - HME, 12.3 [12.2-12.4] mm Hg, P.001; ACD-50 - HME, 4.3 [4.2-4.3] mm Hg, P.001). It was greatest under ATP, less under BTPS, and least with ISO-0.4 and BTPS with 1.2 Vol% isoflurane. In addition to the 100 or 50 mL "volumetric dead space" of each AnaConDa, "reflective dead space" was 40 mL with ACD-100 and 25 mL with ACD-50 when using isoflurane. Isoflurane reflection was highest under ATP. Under BTPS with CO2 insufflation and isoflurane concentrations around 0.4 Vol%, reflection efficiency was 93% with ACD-100 and 80% with ACD-50.Isoflurane reflection remained sufficient with the ACD-50 at clinical anesthetic concentrations, while CO2 elimination was improved. The ACD-50 should be practical for tidal volumes as low as 200 mL, allowing lung-protective ventilation even in small patients.

Economic activities, technological innovation and diffusion, energy consumption and financial development have been significant in BRICS countries over the last three decades. Corresponding to it, BRICS have been facing substantial environmental deterioration. The growth of such factors needs a comprehensive analysis. Hence, this paper examines the impact of technological innovation and diffusion, renewable and non-renewable energy consumption and financial development on ecological footprint under the Kuznets framework in BRICS countries over the time from 1990 to 2018. To confirm the long- and short-run relationship, we apply the second-generation and heterogeneity panel techniques. Where, to measure the impact of technological innovation and diffusion, energy consumption and financial development and other control variable on ecological footprint we use Westerlund Co-integration and pooled mean group (PMG) model for this interest. The results reveal that technological diffusion and non-renewable energy consumption deteriorate environmental quality in the long run. In contrast, renewable energy and technological innovation improve environmental sustainability/quality significantly. Further, results also confirm the existence of the EKC hypothesis. The study suggests that the government should encourage technological innovation and renewable energy consumption to improve environmental quality and achieve the sustainable development goal (SDG).

This study is focused on analyzing the linkage between carbon dioxide (CO2) emissions, renewable energy consumption (RE), foreign direct investment (FDI), national patents (NP), exports (X), imports (M), and gross domestic product (GDP) in Tunisia by using the time series data from 1980 to 2017. A unit root test and an autoregressive distributed lag (ARDL) model were applied to avoid bias caused by data mismatch and autocorrelation of time series data. Elasticity long-run test shows that renewable energy consumption, exports, and gross domestic product have a positive impact on CO2 emissions, while foreign direct investment acts negatively on CO2 emissions. Depending on the error correction term test, there is a long-run causality: from CO2 emissions, renewable energy, foreign direct investment, exports, and gross domestic product to home patent. Findings of the short-run causality show that there is a unidirectional causality running from exports to CO2 emissions and from exports to gross domestic product. Our results also show that Tunisia should encourage foreign direct investment because it seems to be an important factor in the mitigation of CO2 emissions.

The purpose of this work is to study carbon dioxide emissions from the surface of virgin and arable chernozem during the growing season of the Tobol-Ishim interfluve. Methods. The study was conducted on virgin land, in pure steam, under grain crops and corn from May to October. The intensity of carbon dioxide release was determined by the method of Shtatnov with titration in the field. Results. Based on previous studies, based on scientifically based approaches, as well as our own experimental data, the relationship between carbon dioxide emission and hydrothermal conditions of the humus layer (0–30 cm) was investigated, and the degree of influence of the type of land and crops on the release of CO2 from the surface of leached chernozem was determined. It has been established that the chernozems of Western Siberia are characterized by very low biological activity in the spring and autumn periods. CO2 emissions in May averaged 1.0–1.6 kg/ha per hour with a coefficient of variation of 8 %. The peak release of carbon dioxide into the atmosphere occurs in June-July (2.6–6.5 kg/ha per hour). It was revealed that under grain crops the gaseous losses of C–CO2 in the summer period amount to 4.1–6.5 kg/ha per hour, and in the area of pure steam – 2.3–3.4 kg/ha. The determining role in the intensity of carbon dioxide release is played by the soil temperature (r = 0.7). During the years of research, there were no dry periods, which did not allow us to establish a reliable effect of soil moisture on CO2 emissions, the correlation coefficient was 0.2 units. Based on the results obtained, a low degree (12.8 %) of the influence of the type of land (virgin land/arable land) and crops (cereals/corn) on the intensity of carbon dioxide release into the atmosphere from the surface of chernozem was revealed. The maximum degree of influence was in hydrothermal soil conditions (65 %), on which the activity of the soil microbiota and the root system of plants depended. Scientific novelty. For the first time, the intensity of carbon dioxide release from the surface of leached chernozem was studied for the Tobol-Ishim interfluve and the degree of influence of the anthropogenic factor against the background of the hydrothermal regime of soil was established.

The economic structure of countries can influence economic growth, energy demand, and environmental footprints. However, the literature on economic complexity and ecological footprint (EFP) nexus is scarce. Besides, democracy is an important factor that may affect environmental policies and environmental sustainability. Hence, this paper investigates the effect of democracy, economic complexity, and renewable energy technology budgets on the EFP in G7 countries controlling income and financial development from 1985 to 2017. The findings from Westerlund (J Appl Econ 23:193-233, 2008) and other cointegration methods depict cointegration among variables. The long-run estimates from the continuously updated fully modified method unfold that economic complexity contributes to reducing the EFP. However, greater democratic accountability boosts the EFP figures rather than reducing them. On the flipside, renewable energy technology budgets and financial development are evidenced to mitigate EFP. Moreover, the study unveils a U-shaped linkage between economic growth and EFP, which indicates that an increase in income level will boost EFP. Further, the study found causality from economic complexity, democracy, and renewable energy budgets to EFP. Based on these findings, it is pertinent for the G7 countries to increase the manufacturing of sophisticated and complex products. In addition, enhancing renewable energy technology budgets is essential to ensure environmental well-being.

This research for the first time examines the influence of the financial development, stock market, globalization, institutional quality, economic growth, electricity, and renewable energy consumption on carbon dioxide emission from 1985 to 2018 in thirty-six (OECD) countries. Cointegrations exist in the used variables based on the examined findings of the Kao, Westerlund, and Pedroni cointegration. Findings of the pooled mean group (PMG) indicate that renewable energy consumption, globalization, and institutional quality assist to reduce the carbon dioxide emission that improve the environment while financial development, stock market, electricity consumption, and economic growth cause to increase the carbon dioxide emission in OECD countries both in the long and in the short run. To reduce carbon dioxide emission, important policy implications are suggested for OECD countries.

The urgency of dealing with global climate change caused by greenhouse gas(GHG) emissions is increasing as the carbon dioxide(CO2) concentration in the atmosphere has reached a record high value of 416 ppm(parts per million). Technologies that remove CO2 from the surrounding air(direct air capture, DAC) could result in negative carbon emissions, and thus attracts increasing attention. The steady technical progress in adsorption-based CO2 separation greatly advanced the DAC, which largely relies on advanced sorbent materials. This review focuses on the latest development of porous solids for air capture; first discussed the main types of sorbents for air capture, which include porous carbons, zeolites, silica materials, and metal-organic frameworks(MOFs), particularly their modified counterparts. Then, we evaluated their performances, including uptake and selectivity under dry and humid CO2 streams for practical DAC application. Finally, a brief outlook on remaining challenges and potential directions for future DAC development is given.

Fossil fuel electricity generation in Saudi Arabia increased greatly from 1980 to 2017. This paper aims to quantify the electricity generation effect on the environmental quality of Saudi Arabia and explore the role of energy-efficient technological innovation. A structural time series model (STSM) to estimate long-run elasticities and logarithmic mean Divisia index (LMDI) is employed. The results showed that variables (GDP, electricity generation, and population) have a significant effect on carbon dioxide (CO2) emissions. Also, the underlying energy demand trend (UEDT) showed an upward slope for the entire period, which suggests that over the study time there is no improvement in energy efficiency. In decomposing the factors for carbon emissions growth in Saudi Arabia, the findings of applying additive LMDI analysis showed a 1377.56 million tonne (MT) increase in CO2 emissions from the three factors between 1980 and 2017 in the country. The results of additive decomposition showed that the primary factor that drives the carbon emissions growth in Saudi Arabia was the structure effect. Saudi Arabian policymakers could make more informed decisions regarding electricity generation by focusing on increasing energy efficiency and demanding strict environmental regulations to contribute to sustainable economic growth.

Electrocatalytic conversion of CO2 into useful products can contribute to the Paris goals on the basis of abundant low-carbon power and technological advances. From R&D to policy, areas are highlighted in which coordinated efforts can support commercialization of such capture and catalytic technologies while deploying the required infrastructure.

Foreign direct investment (FDI) and remittances are a source of financing that allows the environment to be clean by promoting green innovation. This study empirically examines the impact of financial inflow on renewable energy consumption and environmental quality in BRICS over the period of 1991-2019. The basic results emanate from the NARDL-PMG but robustness observed through FMOLS and DOLS. A positive change in FDI has a positive effect on CO2 emissions, whereas a negative change in FDI significantly reduces CO2 emissions in the long run, while positive and negative shocks to remittance increase the renewable energy consumption in the long run. A positive shock in remittance has no significant impact on CO2 emissions, while a negative shock in remittance leads to an increase in CO2 emissions in the long run. Our results are robust to different econometric methods. The findings of the study have some implications for devising renewable energy consumption and CO2 emission reduction policies in BRICS.

BACKGROUND In mild psoriasis, topical agents remain the mainstay of treatment. However, the available treatments are not satisfactory for a significant proportion of patients in many terms such as efficacy and safety. Because of these deficits, augmentation of therapeutic effect seems desirable. THIS STUDY AIMS To evaluate the efficacy of topical cyclosporine cream, delivered by fractional CO2 laser vs the efficacy of topical clobetasol cream for the treatment of mild to moderate plaque psoriasis. PATIENTS AND METHODS Twenty-two patients with chronic plaque psoriasis involving

Carbon capture and storage is a necessary action for the reduction of CO2 emissions, and thereby mitigation of climate change and its impacts. Especially, in India, with its growing fuel needs and very little attention paid towards carbon capture and storage, mineral carbonation technology is a suitable option as it is cost-effective and could be retrofitted to existing plants that emit CO2. Given the development of carbon capture and storage technology, this study attempts direct mineral carbonation of steelmaking slag with flue gas. Response surface methodology was employed to design gas-solid and slurry phase aqueous carbonation experiments. A maximum reduction of about 36.1% was achieved through aqueous carbonation at 61.1 °C, 46.24 bar, and a liquid-to-solid ratio of 14.5, corresponding to a sequestration capacity of 127.4 g of CO2/kg of slag. The temperature was found to be the most vital parameter in both the aqueous and gas-solid carbonation processes. Regression models used to study the carbonation process were found to be statistically significant. The carbonated slag consisted of mineral phases, namely, calcite and dolomite. The results demonstrated the sequestration potential of Indian steelmaking slag with flue gas. Carbonation of steelmaking slag with flue gas poses to be a promising option for the development of carbon capture and storage technology in the country.

Oman is a Middle Eastern country that has traditionally been monotonically reliant on its indigenous fossil fuel supplies. Besides, the nation has also been a surplus producer and net exporter of oil which further highlights the prolonged fossil fuel dependency of Oman. Consequently, despite flourishing economically, environmental quality in Oman has persistently aggravated. These opposing economic and environmental performances have necessitated Oman to identify the factors which can enable Oman to decarbonize its economy for tackling the environmental concerns faced by the nation. Against this backdrop, this study aims to examine the symmetric and asymmetric effects of foreign direct investments, economic growth, and capital investments on carbon dioxide emissions in Oman during 1980-2019. Using relevant econometric estimation methods for controlling structural break concerns in the data, the findings reveal evidence of asymmetric environmental impacts associated with shocks to the nation's foreign direct investment inflow, economic growth, and capital investment figures. Specifically, it is witnessed that positive shocks to the levels of foreign direct investment inflows, economic growth, and capital investments boost carbon dioxide emissions both in the short and long run. On the other hand, negative shocks to the levels of foreign direct investment inflows and economic growth are witnessed to reduce the emissions. Besides, the findings also validate the environmental Kuznets curve and pollution haven hypotheses in the context of Oman. Hence, considering these key findings, it is recommended that Oman should ideally pursues green economic growth policies by restricting inflows of unclean foreign direct investments and green its financial sector in order to collectively minimize its carbon dioxide emission figures.

Renewable energy is an important alternative energy source in terms of both sustainable growth and climate change. In this paper, the causality nexus between renewable energy consumption and economic growth is analyzed in 15 emerging countries covering the period from 1990 to 2015. The paper adopts the bootstrap panel causality test which is developed by (Kónya, Econ Model 23:978-992, 2006) to consider the cross-sectional dependence. The results of (Kónya, Econ Model 23:978-992, 2006) prove the validity of the neutrality hypothesis in all countries. Then, we analyze asymmetric causality among the variables. Asymmetric test denotes a causality from negative shocks of economic growth to negative shocks of renewable energy consumption in South Africa, Thailand, and Turkey. Thus, a negative shock in economic growth hampers renewable energy consumption in these countries. Our results demonstrate the consequences of the application of disaggregated data in the analyses.

Human activity is the main cause of climate change. People burn fossil fuels and convert land from forests to agriculture. Burning fossil fuels produces carbon dioxide, a greenhouse gas. Climate change due to vehicular movements, industries, and deforestation for creating newer inhabitations affects the environmental and social determinants of health. An effective public health response to climate change is involves preventing injuries and illnesses, escalating public health preparedness, and reducing risk of consequences of all listed climate change immediate support, manage health effects and outbreaks. The world leaders are gathering in Glasgow for COP26, today the October 31st, 2021, to carry forwards the unfinished agenda. The process is ruled by arriving at consensus, and the pace is set by the least willing countries. In 2019, developed countries provided $16.7 billion as a grant, that amounts to just $1 per month for climate finance. Developed countries can surely afford more than this. A credible climate finance plan from them is, therefore, crucial. The world’s 20 biggest economies recently endorsed a landmark deal on a global minimum corporate tax rate of 15% and will aim to implement the rules by 2023 for climate financing. The main reason why cop26 process matters is that the science, diplomacy, activism, and public opinion that support it make up the best mechanism the world currently must help it come to terms with a fundamental truth. Looking at the progress made since the imitation of COP so far and minimal groundwork that has been done to achieve them, most of the demands may not be met. India’s ambitious 450 GW renewable energy goal by 2030, its hydrogen mission, plan to move Indian railways to ‘net-zero’ emission by 2030, land degradation neutrality and massive programme to increase forest cover- natural carbon sink the key points the country will commit to drive home. Forty-five nations pledged to step up protection of nature and overhaul farming to cut greenhouse gas emissions, but major economies led by the US, Japan and Germany and developing nations such as India, Indonesia, Morocco, Vietnam, Philippines, Gabon, Ethiopia, Ghana, and Uruguay backed from commitments. The steps include leveraging over $4 billion of new public sector investment into agricultural innovation, including the development of climate-resilient crops and regenerative solutions to improve soil health. I think climate challenges will be met, not because of summits and global idealism but because of enormous sums likely to be spent on green innovation by profit-driven corporations, incentivised by modest government subsidies and mandates Material & methods: This article is a review of available literature on Impact of climate change on health and global Climate change efforts, in press and various government and UN agency documents.

Background For children and adults, the standard treatment for obstructive sleep apnea is the delivery of continuous positive airway pressure (CPAP). Though effective, CPAP masks can be uncomfortable to patients, contributing to adherence concerns. Recently, nasal high flow (NHF) therapy has been investigated as an alternative, especially in CPAP-intolerant children. The present study aimed to compare and contrast the positive airway pressures and expired gas washout generated by NHF versus CPAP in child nasal airway replicas. Methods NHF therapy was investigated at a flow rate of 20 L/min and compared to CPAP at 5 cmH2O and 10 cmH2O for 10 nasal airway replicas, built from computed tomography scans of children aged 4–8 years. NHF was delivered with three different high flow nasal cannula models provided by the same manufacturer, and CPAP was delivered with a sealed nasal mask. Tidal breathing through each replica was imposed using a lung simulator, and airway pressure at the trachea was recorded over time. For expired gas washout measurements, carbon dioxide was injected at the lung simulator, and end-tidal carbon dioxide (EtCO2) was measured at the trachea. Changes in EtCO2 compared to baseline values (no intervention) were assessed. Results NHF therapy generated an average positive end-expiratory pressure (PEEP) of 5.17 ± 2.09 cmH2O (mean ± SD, n = 10), similar to PEEP of 4.95 ± 0.03 cmH2O generated by nominally 5 cmH2O CPAP. Variation in tracheal pressure was higher between airway replicas for NHF compared to CPAP. EtCO2 decreased from baseline during administration of NHF, whereas it increased during CPAP. No statistical difference in tracheal pressure nor EtCO2 was found between the three high flow nasal cannulas. Conclusion In child airway replicas, NHF at 20 L/min generated average PEEP similar to CPAP at 5 cm H2O. Variation in tracheal pressure was higher between airway replicas for NHF than for CPAP. The delivery of NHF yielded expired gas washout, whereas CPAP impeded expired gas washout due to the increased dead space of the sealed mask.

Recently, many studies have been conducted on the conversion of conventional fossil fuels to alternative fuels. Natural gas is one of the best alternative fuels because it is a low-carbon fuel. In natural gas engines, port fuel injection is generally adopted rather than direct injection because of the compatibility of the injection system in a positive ignition engine. However, methane, of which the global warming potential is 28 times than that of carbon dioxide, is highly likely to emit during the valve overlap in port fuel injection engines. The methane slip phenomenon could be reduced by changing the intake and exhaust valve timing. However, few studies have discussed engine performance and emission characteristics through valve timing changes in natural gas engines. Therefore, in this study, experiments were conducted under the valve timing variations with/without boosting in a natural gas engine. Through experiments, it was possible to investigate the trend of engine performance and methane emission according to the change in the intake and exhaust valve timing. As a result, under the boosted condition, the intake valve timing could only be advanced up to 45 CAD bTDC and the exhaust valve timing could only be retarded by 27.4 CAD bBDC. This is because the methane slip phenomenon increased and it resulted in a decrease of engine torque when the intake valve timing was excessively advanced or the exhaust valve timing was inordinately retarded under the boosted condition. In addition, considering a level of methane emission equivalent to EURO-6, the valve timings were optimized for each engine speed point of 1000–2500 rpm under boosted high load conditions. It was found that the trend of intake valve timing of the natural gas engine was unlike that of the conventional gasoline engine under the low engine speed of less than 2500 rpm.

Accompanying with the rapid consumption of fossil fuel resources, a huge amount of CO2 has being released into the atmosphere, which brings serious environmental concerns. However, CO2 can also be considered as a clean and non-toxic carbon resource; the utilization of CO2 by converting it into various hydrocarbons can not only alleviate the greenhouse effect, but also provide a new sustainable route to produce clean fuel and chemical products. In this paper, we attempt to make a review on the recent research progresses in the hydrogenation of CO2 to certain hydrocarbons (including methane, olefins and aromatics) in recent years; in particular, the advance in the development of efficient catalysts for the hydrogenation of CO2 to methane, light olefins and aromatics as well as in the exploration of catalytic reaction mechanisms were retrospectively summarized. Lastly, we would like to have an outlook on the possible trends in the utilization of CO2 as a carbon resource through hydrogenation.

Graphical abstract A massive increase in the use and production of masks worldwide has been seen in the current COVID-19 pandemic, which has contributed to reducing the transmission of the virus globally. This paper aims to evaluate the life cycle environmental impacts of disposable medical masks to identify the life cycle stages that cause the highest impact on the environment. A further goal is to estimate the total environmental impacts at the global level in 2020. The inventory data was constructed directly from the industry. The system boundary of the study is from cradle to grave comprising raw material extraction and processing, production, packaging, distribution, use, and disposal as well as transport and waste management along the supply chain. Eleven environmental impacts have been estimated. The results suggest that the global warming potential of a disposable medical mask is 0.02 g CO2-eq. for which the main contributor is the raw material supply (40.5%) followed by the packaging (30.0%) and production (15.5%). Sensitivity analysis was carried out to test the environmental impacts. In total, 52 billion disposable medical masks used worldwide consumes 22 TJ of energy in 2020. The global warming potential of disposable medical masks supplied in a year of the COVID-19 pandemic is 1.1 Mt CO2 eq. This paper assessed the hotspots in the medical mask. The findings of this study will be of interest to policymakers, global mask manufacturers, and users, allowing them to make more informed decisions about the medical mask industry.

The database of the Global Trade Analysis Project (GTAP) and its energy–environmental model, known as GTAP-E, are used in this study to simulate the effect of the simultaneous and separate carbon tariff impositions of EU, the USA, and Japan on the export and export structure in China. Simulation results show that the carbon tariff impositions of developed countries on China will decrease the export to EU, the USA, and Japan but increase the export of China to other countries associated with the trade diversion in China. The USA and EU impose carbon tariffs on China, which will have a serious impact on China’s export trade, especially for the export trade of energy-intensive industries. When Japan imposes carbon tariff on the exports of China, the positive influence on the export trade is weaker compared to the situation that the USA and EU imposed on China. Furthermore, imposing carbon tariffs on China will improve its trade structure; promote its agriculture, petroleum, and natural gas exploration and electricity industries; reduce its export trade volume of coal mining, petroleum products, and energy-intensive and other industries; decrease the export trade share of energy-intensive industries; and increase the export trade share and services of other industries. In this regard, China should reduce the carbon content of export products initiatively. On the one hand, China can solve this problem by levying carbon tax, developing emerging industries, and strengthening the research and development of low-carbon technologies. On the other hand, China should actively participate in the formulation of international standards of carbon tariff and become a participant in the international emission reduction rules in the field of climate change.

The aim of study is to estimate the role of energy financing for energy retrofit in COVID-19, with the intervening role of green bond financing. For this, Kalman technique is applied to infer the empirical findings. It is found that energy financing is significantly dependent on green bonds, and green bonds have a significant role in energy retrofit in E-7 economies specifically. It is further found that E-7 economies gained significant rise in energy efficiency financing green bonds financing, that has supportively extended energy retrofit - before and during COVID-19 crises. It is further found significant that the E-7 nations have to put alot of money into hydro and nuclear energy for energy retrofit, with low carbon emissions. In the light of COVID-19 crises, this study offers policy recommendations for effective energy management. However, such policy recommendations are expected to finely serve the financial intermediaries and national governments of E-7 economies to better optimize energy financing through green bond financing. The novelty of the study exists in topical framework and research directions, talking about the way forwards for energy efficiency financing - which is one of the latest issue of the recent times. Hence, this research provides some empirical verifications about energy financing in COVID-19 crises for energy retrofit, and shares some suggestions for stakeholders.

Natural gas hydrate (NGH), as a clean energy with great development potential, has been limited by the lack of efficient and safe exploitation methods for a long time. The CO2 displacement method proposed in recent years has not made substantial progress because of its poor permeability and low efficiency. The NH3 replacement method is proposed in this paper because of its strong permeability. We performed orthogonal molecular dynamics simulation of the replacement of CH4 in hydrate with NH3 and CO2 at different temperatures (245 K, 255 K, 265 K) and pressures (3 MPa, 5 MPa, 10 MPa). It is shown that:(1) Compared with CO2 molecules, NH3 and can penetrate into the hydrate layer effectively, and the resulting pore channels are conducive to the outward diffusion of CH4 molecules. (2) With the progress of the replacement process, the hydrate structure gradually decomposes but not completely, and the residual structure will inhibit the diffusion of CH4 molecules and lead to the agglomeration of CH4 molecules. (3) Within 1000 ps, the number of CH4 molecules replaced by NH3 is more than that of CO2 under the conditions of 245 K and 255 K, and less than that of CO2 under the conditions of 265 K. At the same temperature, the pressure does not affect the final comparison result.

Abstract Background Electrical muscle stimulation (EMS) induces involuntary muscle contraction. Several studies have suggested that EMS has the potential to be an alternative method of voluntary exercise; however, its effects on cerebral blood flow (CBF) when applied to large lower limb muscles are poorly understood. Thus, the purpose of this study was to examine the effects of EMS on CBF, focusing on whether the effects differ between the internal carotid (ICA) and vertebral (VA) arteries. Methods The participants performed the experiments under EMS and control (rest) conditions in a randomized crossover design. The ICA and VA blood flow were measured before and during EMS or control. Heart rate, blood pressure, minute ventilation, oxygen uptake, and end-tidal partial pressure of carbon dioxide (PETCO2) were monitored and measured as well. Results The ICA blood flow increased during EMS [Pre: 330 ± 69 mL min−1; EMS: 371 ± 81 mL min−1, P = 0.001, effect size (Cohen’s d) = 0.55]. In contrast, the VA blood flow did not change during EMS (Pre: 125 ± 47 mL min−1; EMS: 130 ± 45 mL min−1, P = 0.26, effect size = 0.12). In the EMS condition, there was a significant positive linear correlation between ΔPETCO2 and ΔICA blood flow (R = 0.74, P = 0.02). No relationships were observed between ΔPETCO2 and ΔVA blood flow (linear: R = − 0.17, P = 0.66; quadratic: R = 0.43, P = 0.55). Conclusions The present results indicate that EMS increased ICA blood flow but not VA blood flow, suggesting that the effects of EMS on cerebral perfusion differ between anterior and posterior cerebral circulation, primarily due to the differences in cerebrovascular response to CO2.

Human activities such as deforestation and cultivation contribute to the accumulation of carbon dioxide in the environment. Methane is emitted by energy exploration, coal mining, natural gas spills, waste, and waste dumps. Methane generated by such greenhouse gases has significantly contributed to the climate change and global warming. However, the most significant contributor to climate change and global warming is the use of fossil fuels. These fuels contribute to ozone depletion and global warming by emitting greenhouse gases into the atmosphere. The current study key objective was to determine the CO2 emission effect to key fruit production in Pakistan by taking time series annual data varies from 1970 to 2019. A non-linear autoregressive distributed lag model (NARDL) was employed to check the variables linkages. The consequences of short- and long-run estimates expose that the positive and adverse shocks of citrus fruit create expressively to upsurge the CO2 emission. Similarly, the positive and negative shocks of mango fruit expose an adverse interaction to CO2 emission. The positive shock of apple fruit has constructive but negative shock expose and adverse linkage to CO2 emission. Further, banana fruit also exposes a negative but constructive via positive shock linkage to CO2 emission. Moving towards the apricot fruit production that exposed a constructive linkage via positive and negative shocks to CO2 emission. The almond fruit productivity via positive and negative shocks exposed an adverse relation to carbon dioxide emission. Grape fruit via positive shock shows a construct, but negative shock exposed an adverse association to carbon emission in Pakistan. Finally the guava fruit production exposed a construct linkage to CO2 emission via positive and negative shocks. Since agricultural activities and CO2 emissions are essential to resolving the pollution problem, a series of practicable steps must be taken by the Pakistani authorities to tackle this issue.