Production Ratio Research Articles

Nitrogen migration and transformation during the pyrolysis of corn straw with iron-based catalyst

The pyrolysis of renewable biomass into biofuels and high-value chemicals showcases remarkable application value and extensive market potential. However, the pyrolysis of biomass with high nitrogen content results in the production of NOX precursors that contribute to environmental pollution. Therefore, it is proposed to introduce iron-based catalysts to change the formation pathway of NOX precursors and control their production.The study elucidates the influence of iron-based catalysts on the conversion of nitrogen-containing products between gas, liquid and solid phases during corn straw pyrolysis. First, the effects of iron-based catalyst types on pyrolysis kinetics of corn straw were estimated using Thermogravimetry-mass spectrometry (TG-MS). Based on this, the effects of catalyst type and dispersion on the migration path of three-phase nitrogen-containing products were investigated, and the chemical morphology of the catalyst during pyrolysis was monitored by in-situ XRD to clarify the main catalytic active phase for N2 formation. Results showed that the addition of Fe, FeCl3 and Fe2O3 changed the distribution ratio of three-phase nitrogen-containing products, and the gas phase yield was significantly improved. Notably, the chemical form of Fe2O3 will change and transform into FeOOH, Fe3O4 and α-Fe during pyrolysis. It was confirmed that α-Fe was the main active phase for catalyzing the conversion of nitrogen-containing substances. Higher N2 conversion can be achieved by preparing high purity α-Fe. The mechanism is that α-Fe catalyzes the secondary decomposition of tar nitrogen into NH3 and HCN. Simultaneously, α-Fe reacts with char nitrogen, NH3, and HCN to form FeXN, which decomposes to produce environmentally friendly N2. The research findings offer theoretical guidance for the control of nitrogen pollutant emissions and the targeted acquisition of pyrolysis products (For example, NH3 can be used as a carbon-free hydrogen-rich fue).

Degradation pathways and product formation mechanisms of asphaltene in supercritical water

Asphaltene is the compound with the most complex structure and the most difficult degradation in oily sludge, which is the key to limit the efficiency of supercritical water oxidation treatment of oily sludge. In this paper, the supercritical water oxidation process of asphaltene was investigated in terms of free radical reaction, degradation pathway, and product generation mechanism using ReaxFF molecular dynamics simulation method. The results showed that increasing temperature, increasing O2, and increasing H2O have different effects on HO2·generation. Benzene rings undergo fusion and condensation through hydrogenation abstraction and oxygen addition reactions, subsequently breaking down into long-chain alkanes. Increasing O2 can effectively promote the ring-opening of nitrogen-containing heterocycles. -COOH is the most important intermediate fragment for CO and CO2 generation, and there is a reaction competition with -CHO3 and -CO3. When the number of oxygen molecules increases from 300 to 700, the reaction frequency of -CHO3 and -CO3 to generate CO and CO2 increases by 17.14 % and 12.77 %·H2O determines the production of H2 by controlling the number of H·radicals present. As the amount of H2O increases from 500 to 1500, the product ratio of H2 increases from 12.73 % to 21.31 %. Environmental implicationAsphaltene is the most structurally complex organic matter in oily sludge, and its presence makes it difficult for oily sludge to be completely degraded by conventional treatment methods such as pyrolysis and incineration. Polycyclic aromatic hydrocarbons (PAHs) represented by asphaltene increase the carcinogenicity and mutagenicity of oily sludge, and even irreversibly pollute soil and groundwater. Supercritical water oxidation, as an efficient organic waste treatment technology, can realize harmlessness in a green and efficient way. So the study on the mechanism of supercritical water oxidation of asphaltene is of great significance for environmental protection.

Multi-Physics Modeling and the Sensitivity Analysis for the Critical Factors in Solid Oxide CO2-Steam Co-Electrolysis System Performances

A multi-physics modeling framework, which includes electrochemical and chemical reactions, mass transfer, and energy balance, has been developed and validated against experiment measurements to investigate the performance of solid oxide CO2-steam co-electrolysis (SOEC) under various operating conditions and cell designs. However, multi-physics modeling for complex SOEC systems can be computationally expensive and not tractable for general system design and optimization. Reduced-order models (ROMs) have been proven as a powerful tool for reducing computational costs, closely mimic the high-fidelity SOEC stack models and identify the operational condition parameters to which the SOEC stack is sensitive and needs appropriate controls for stable operation. In this study, the deep neural networks (DNN) algorithm is employed to construct ROMs according to multi-physics simulations for SOECs to systematically investigate the SOECs’ electrochemical performance and rank the contributions of operational condition parameters for both 2 cm2 button cell and 300 cm2 planar cells. Sensitivity analysis reveals that cell voltage, fuel composition (denoted by CO2/H2O ratio), and the operating temperature impact the cell performance most. The product ratio ΔCO/ΔH2 has a stronger dependence on the CO2/H2O ratio in the fuel compositions than on other operating condition parameters. The large 300 cm2 planar cells were modeled under both adiabatic and furnace environment. The simulation and sensitivity analysis indicate that the large cell operating in adiabatic environment usually provides relatively lower performances than the one in furnace environment. Additionally, the adiabatic environment also causes the cell’s performances are more sensitive to the operation conditions, such as external voltage, fuel flow rate, and fuel compositions. The large cell in adiabatic environment also leads to higher internal temperature variation, which may impact the structure reliability.

Modeling Silver Corrosion Mechanisms in Marine Atmospheric Environments

Measures that can assess the severity of the local environment are an important tool for combating atmospheric corrosion. One approach for determining the environmental severity employs electrochemical analysis alongside surface characterization on silver coupons exposed to the environment for varying durations. However, despite the long use of silver as an environmental severity monitor, the underlying reaction mechanisms that give rise to the observed corrosion products are not well understood. In addition, the measured ratios of silver corrosion products appear to be unique to the location where the silver coupons were exposed.The goal of this work is to develop models of silver oxidation reactions that can explore pathways for the formation of silver corrosion products. We use density functional theory (DFT) calculations in nudged elastic band (NEB) approximations to determine electrochemical and chemical reaction along with surface diffusion energy barriers. An example reaction is shown in Figure 1a and b, in which an O2 molecule is adsorbed on an ‘on-top’ site on a relaxed Ag (100) crystal structure with periodic boundary conditions in the x and y-planes. The O2 molecule then dissociates into individual O atoms. The reaction pathway is approximated using the NEB approach to determine the dissociation energy barrier in Figure 1c. These reaction energy barriers are incorporated into a kinetic Monte Carlo (KMC) model of silver reactions to estimate the corrosion products present in marine atmospheric environments for comparison with experimental data. Figure 1

Probing the Activity and Selectivity of Nickel Carboxylethylphosphonate 2D-MOF for the Electrochemical Conversion of CO2 to Syngas

The increasing concentration of CO2 in the atmosphere is alarming for modern society and the reduction of CO2 into valuable products would be a unique solution.1 Metal–organic frameworks (MOFs), constructed from organic linkers interconnected with metal (oxide) nodes, with high porosity and large surface area, have become an emerging class of electrocatalysts for reduction of CO2.2,3 Herein, we report the synthesis and characterization of a two-dimensional nickel metal-organic framework (2D Ni-MOF) with 3-phosphopropionic acid and 4,4-bypyridine as ligands and Ni2+ as the node (figure 1). The electrocatalytic activity of this material is explored for the electrochemical CO2 reduction reaction (CO2RR). An onset potential for the electrochemical reduction CO2 activity of -0.51 V vs RHE was observed which is 70 mV more positive than the HER in Ar-saturated electrolyte suggesting an efficient CO2 reduction. This catalyst showed a high current density of 33.5 mA cm-2 at 1.01 V vs RHE, exhibiting superior performance to most of the MOFs tested so far for CO2 reduction (figure 2a and b). Long term electrolysis at -0.8 V (vs RHE) yielded a current density of ∼10 mA cm-2 with high selectivity towards the formation of CO and H2 with an average production ratio of 30:70%, respectively (figure 2c and d). This new Ni-MOF catalyst retained its crystallinity and morphology after electrolysis as confirmed by powder XRD, HRTEM, FT-IR and Raman spectroscopy, indicating promising stability of the catalyst.Density functional theory (DFT) was employed to calculate adsorption-free energy of the reaction intermediates to identify the active catalytic sites responsible for CO2 reduction in our 2D Ni-MOF structure. Findings show that the catalyst more readily reduces H* to H2 (with a limiting potential of 0.48 eV) than CO2 to COOH* (limiting potential of 0.78 eV). The reaction mechanism upon which this calculation was based begins with the removal of the H2O molecule bound to the Ni (II) site, followed by CO2 adsorption and the two proton-coupled electron transfer steps yielded COOH* and then CO & H2O. The H2O is more strongly adsorbed to the Ni (II) site than CO which closes the mechanistic cycle. Reference 1. M. J. B. Kabeyi and O. A. Olanrewaju, Frontiers in Energy Research, 2022, 9.2. B.-X. Dong, S.-L. Qian, F.-Y. Bu, Y.-C. Wu, L.-G. Feng, Y.-L. Teng, W.-L. Liu and Z.-W. Li, ACS Applied Energy Materials, 2018, 1, 4662-4669.3. J.-X. Wu, S.-Z. Hou, X.-D. Zhang, M. Xu, H.-F. Yang, P.-S. Cao and Z.-Y. Gu, Chemical Science, 2019, 10, 2199-2205. Figure 1

An assessment of the vulnerability and adaptation potential of sugarcane production to water stress, southern Africa

The high spatial variability of precipitation, heightened frequency of droughts and concomitant increases in exposure to water stress across southern Africa due to climate change, presents significant challenges for sugarcane production and the regional sugarcane production value chain. While production has intensified in the past few decades, yields have declined due to increased climatic variability and agronomic management approaches. Increased precipitation variability has enhanced sugarcane vulnerability to water stress and is likely to negatively affect yields. Combining crop simulations and relationships between sugarcane water use and observed rainfall, we introduce a crop productivity ratio (CPR) which assesses sugarcane water stress for six sugarcane mills across southern Africa. The CPR and simulation results were used to assess the adaptation potential or ‘space’ for mill areas that have varying rates of exposure and abilities to adapt to water stress. Simulation results were used to determine the long-term adaption potential of mill areas and to surmise the causes of yield declines. The results were used to offer recommendations to reduce vulnerabilities and enhance adaptation to water stress. We conclude that the amplification of inter-annual precipitation variability will enhance the exposure of sugarcane to water stress and require adaptation interventions. Adapting to external shocks is a multifaceted exercise that requires a holistic approach that includes every aspect of the sugarcane value chain.

CircNAP1L4 regulates pulmonary artery smooth muscle cell proliferation via the NAP1L4-mediated super-enhancer-driven glycolysis gene hexokinase II (HK II) in pulmonary hypertension.

Glycolysis is a major determinant of pulmonary artery smooth muscle cell (PASMC) proliferation in pulmonary hypertension (PH). Circular RNAs (circRNAs) are powerful regulators of glycolysis in multiple diseases; however, the role of circRNAs in glycolysis in PH has been poorly characterized. The aim of this study was to uncover the regulatory mechanism of a new circRNA, circNAP1L4, in human pulmonary artery smooth muscle cell (HPASMC) proliferation through the host protein NAP1L4 to regulate the super-enhancer-driven glycolysis gene hexokinase II (HK II). CircNAP1L4 was downregulated in hypoxic HPASMCs and plasma of PH patients. Functionally, circNAP1L4 overexpression inhibited glycolysis and proliferation in hypoxic HPASMCs. Mechanistically, circNAP1L4 directly bound to its host protein NAP1L4 and affected the ability of NAP1L4 to move into the nucleus to regulate the epigenomic signals of the super-enhancer of HK II. Intriguingly, circNAP1L4 overexpression inhibited the proliferation but not the migration of human pulmonary arterial endothelial cells (HPAECs) cocultured with HPASMCs. Furthermore, pre-mRNA-processing-splicing Factor 8 (PRP8) was found to regulate the production ratio of circNAP1L4 and linear NAP1L4. Invivo, targeting circNAP1L4 alleviates SU5416 combined with hypoxia (SuHx)-induced PH. Overall, these findings reveal a new circRNA that inhibits PASMC proliferation and serves as a therapeutic target for PH.

Catalytic pyrolysis of apricot kernel shell over metal supported MCM-41 catalysts obtained by synthesizing sonochemical method

In this study, it is targeted to examine the efficiency of metal supported MCM-41 catalysts on the liquid product yield from pyrolysis process of apricot kernel shell selected as a biomass and to characterize the pyrolysis liquids. In the non-catalytic pyrolysis experiments, the maximum liquid yield is obtained as 21.41 % at 500 °C. At the determined optimum condition, catalytic pyrolysis process of the biomass sample is performed with metal supported MCM-41 catalysts synthesized by sonochemical method (metal: aluminium, cobalt, iron) at different ratios to biomass (1 and 2 wt %). The pyrolysis procedures of apricot kernel shell are carried out in a tubular fixed-bed reactor at different pyrolysis temperatures. The use of catalysts improved both the liquid product (tar) yield and tar quality in respect to the calorific value, the distribution of hydrocarbons and the elimination of oxygenated groups. The results revealed that all metal-supported MCM-41 catalysts, especially the Fe-MCM-41 catalyst ratio of 2, showed an excellent catalytic ability for thermal conversion of biomass. In the catalytic pyrolysis experiments carried out at 500 °C, 75.84 % conversion to liquid and gaseous products was obtained using 2 % Fe-MCM-41 catalyst, and the calorific value of the liquid product obtained was determined as 40.96 MJ/kg. The functional group analyses in the structure of the liquid products are characterized using FT-IR spectroscopy, and the distributions of the aliphatic/aromatic fractions of the liquid products are characterized using GC-MS technique. The H/C ratio of the liquid product obtained from catalytic pyrolysis is between light and heavy petroleum products and also has lower oxygen content and higher calorific value, indicating the potential of metal-supported MCM-41 catalyst for renewable hydrocarbon production from apricot kernel shell.

Photo-Thermal Dry Reforming of Methane with PGM-Free and PGM-Based Catalysts: A Review.

Dry reforming of methane (DRM) is considered one of the most promising technologies for efficient greenhouse gas management thanks to the fact that through this reaction, it is possible to reduce CO2 and CH4 to obtain syngas, a mixture of H2 and CO, with a suitable ratio for the Fischer-Tropsch production of long-chain hydrocarbons. Two other main processes can yield H2 from CH4, i.e., Steam Reforming of Methane (SRM) and Partial Oxidation of Methane (POM), even though, not having CO2 as a reagent, they are considered less green. Recently, scientists' challenge is to overcome the many drawbacks of DRM reactions, i.e., the use of precious metal-based catalysts, the high temperatures of the process, metal particle sintering and carbon deposition on the catalysts' surfaces. To overcome these issues, one proposed solution is to implement photo-thermal dry reforming of methane in which irradiation with light is used in combination with heating to improve the efficiency of the process. In this paper, we review the work of several groups aiming to investigate the pivotal promoting role of light radiation in DRM. Focus is also placed on the catalysts' design and the progress needed for bringing DRM to an industrial scale.

The preparation of hydrated magnesium carboxylate cement and the properties of its bonded castables

The hydrated magnesium carboxylate cement (HMC) with varying C6H5O72−/Mg2+ ratios was prepared by adjusting the ratio of citric acid to magnesia in this study, and its effect on the performances of corundum-spinel refractory castables were investigated. The results revealed that the HMC bonded castable's workability was improved by increasing the C₆H₅O₇³⁻/Mg2⁺ ratio. Specifically, the sample C-EX (citric acid/magnesia = 4.5) compared to the standard sample NO (citric acid/magnesia = 3.5), the setting time was extended by 100 min, and the flow value increased by 77.6 %. Hydration kinetics experiments demonstrate that this phenomenon was due to the excess citric acid inhibiting HMC ionization. Furthermore, increasing the C₆H₅O₇³⁻/Mg2⁺ ratio also enhanced castables' medium-temperature mechanical properties and thermal shock resistance. The excess citric acid enhanced the castable slurry's performance, resulting in a 37.8 % increase in cold modulus of rupture for the C-EX sample after sintering at 500 °C compared to the sample NO. The fracture strength after thermal shock is 27.9 % higher in sample C-EX than in sample NO. This improvement is attributed to the 82.1 % increase in toughness of the sample C-EX, which facilitates the micro-cracks formation but inhibits their propagation. However, it should be noted that increasing the proportion of citric acid reduced the aspect ratio of HMC hydration products, leading to decreased mechanical properties of the castables.

Effect of soaking conditions on physicochemical properties and sensory quality of cooked glutinous rice with an electric rice cooker

This research aimed to investigate the changes in physicochemical properties and sensory qualities of cooked glutinous rice (RD6) by using the electric rice cooker method with different soaking conditions compared to cooking glutinous rice by steaming in a conventional steamer (control). Glutinous rice grain was soaked at different soaking conditions of temperatures at 25 and 45°C and soaking time for 30, 60, and 90 min, and then were cooked by the electric rice cooker. The results indicated that the degree of starch gelatinization was increasingly correlated with the moisture content and water activity of the cooked waxy rice. Moreover, with the increase in the degree of gelatinization, the hardness value exhibited a decreasing trend, and the adhesiveness value increased. The L* (lightness), a* (redness), and whiteness index of cooked glutinous rice increased when the temperature and time of soaking increased, while the color intensity decreased. The overall acceptability scores indicated that the lower soaking time obtained a higher score for cooked glutinous rice. Compared with the control sample, the soaking conditions for the temperature and time of 25°C/30 min or 45°C/30 min are viewed as a suitable ratio of a good quality product for cooked glutinous rice by using the electric rice cooker method, in which rice cooking provided the high score of overall acceptability on consumer preference.

Effect of soaking conditions on physicochemical properties and sensory quality of cooked glutinous rice with an electric rice cooker

This research aimed to investigate the changes in physicochemical properties and sensory qualities of cooked glutinous rice (RD6) by using the electric rice cooker method with different soaking conditions compared to cooking glutinous rice by steaming in a conventional steamer (control). Glutinous rice grain was soaked at different soaking conditions of temperatures at 25 and 45°C and soaking time for 30, 60, and 90 min, and then were cooked by the electric rice cooker. The results indicated that the degree of starch gelatinization was increasingly correlated with the moisture content and water activity of the cooked waxy rice. Moreover, with the increase in the degree of gelatinization, the hardness value exhibited a decreasing trend, and the adhesiveness value increased. The L* (lightness), a* (redness), and whiteness index of cooked glutinous rice increased when the temperature and time of soaking increased, while the color intensity decreased. The overall acceptability scores indicated that the lower soaking time obtained a higher score for cooked glutinous rice. Compared with the control sample, the soaking conditions for the temperature and time of 25°C/30 min or 45°C/30 min are viewed as a suitable ratio of a good quality product for cooked glutinous rice by using the electric rice cooker method, in which rice cooking provided the high score of overall acceptability on consumer preference.

Sensory Characteristics of Meat Sausage Products with Modified Cassava Flour as Filler

The use of modified cassava starch and flour in this study aims to obtain the optimal concentration of modified cassava starch and flour ratio in meat sausage emulsion type products and characterize organoleptic properties in meat sausage emulsion type products using modified cassava starch and flour as fillers. The ingredients used are modified cassava starch and flour, beef obtained from the Son Haji Sonny Bandar Lampung slaughterhouse, chicken meat from PT. Ciomas Adisatwa Lampung, sausage sleeves, and seasonings used in making beef sausages. The treatment given is a ratio of starch:modified cassava flour with a ratio of 90:10; 80:20; 70:30; and 60:40. The sensory test results showed that the most preferred sensory characteristics of sausages were sausages with a modified 80:20 starch:cassava flour ratio treatment for the sensory characteristics of sausage taste and texture. As for color sensory characteristics at a ratio of 60:40; and for aroma sensory characteristics at a ratio of 70:30. From the sensory characteristics that are closer to the quality characteristics of sausages are texture and taste, it can be concluded that the most preferred sausage is sausage with the addition of starch and modified cassava flour in a ratio of 80: 20.

Smad4 and FoxH1 potentially interact to regulate cyp19a1a promoter in the ovary of ricefield eel (Monopterus albus)

BackgroundCyp19a1a is a key enzyme in the pathway that converts androgens into estrogen and is regulated by TGF-β signaling. Smad4 and FoxH1 are downstream effectors of TGF-β signaling and may play important roles in ovarian development in M. albus.MethodsWe investigated the expression pattern of the Smad4 and FoxH1 using qRT‒PCR and immunofluorescence, then tested the changes of smad4 and foxh1 by qRT‒PCR after ovary incubation with FSH in vitro, and analysed the regulation of cyp19a1a transcription by Smad4 and FoxH1 by dual-luciferase reporter assays.ResultsWe found that Smad4 encoded a putative protein of 449 amino acids and harbored the three conserved domains typical of this protein family. Smad4 and foxh1 exhibited similar expression patterns during ovarian development and after FSH incubation, with Pearson’s coefficients of 0.873 and 0.63–0.81, respectively. Furthermore, Smad4, FoxH1 and Cyp19a1a colocalized in the granulosa cells and theca cells of ovaries during the mid-to-late vitellogenic stage. Smad4 repressed cyp19a1a activity via SBE1 (− 1372/−1364) and SBE2 (− 415/−407) in the cyp19a1a promoter, whereas mutating SBE1 or SBE2 restored cyp19a1a promoter activity. Co-overexpression of Smad4 and FoxH1 significantly reduced cyp19a1a promoter activity.ConclusionsThis study provides new insights into the potential functions of transcription factors Smad4 and FoxH1 in ovarian development and the transcriptional regulation mechanism of cyp19a1a in M. albus, which will reveal Smad4/FoxH1-mediated TGF-β signaling in reproduction and the regulation of the cyp19a1a.Plain English summaryAromatase, encoded by cyp19a1a, is involved in ovarian development and plays an important role in the quality of eggs, as well the sex ratio, of the teleost fish, M. albus. The research on the transcriptional regulation of cyp19a1a has contributed to the understanding of its role in ovarian development. In previous study, it was shown that FoxH1 inhibits cyp19a1a transcription. In the present study, Smad4 was confirmed as a cyp19a1a transcriptional repressor and Smad4 may also coordinate with FoxH1 to repress cyp19a1a transcription. At present, we provide a new perspective for the transcriptional regulation of cyp19a1a by transcription factors Smad4 and FoxH1 in teleost fish ovary. In the future, the regulatory networks of Smad4 and FoxH1 will be further studied and the gene editing technology will be applied to screen specific regulatory factors of cyp191a1a gene, so as to alter the female cycle and modulate the sex ratio of the eggs production.

Real-time performance improvement optimizes damage control resuscitation best practice adherence: Results of a pilot prospective observational study.

Maintaining balanced blood product ratios during damage control resuscitation (DCR) is independently associated with improved survival. We hypothesized that real-time performance improvement (RT-PI) would increase adherence to DCR best practice. From December 2020-August 2021, we prospectively used a bedside RT-PI tool to guide DCR in severely injured patients surviving at least 30 min. RT-PI study patients were compared to contemporary control patients at our institution and historic PROMMTT study patients. A subset of patients transfused ≥6 U red blood cells (RBC) in 6 h (MT+) was also identified. The primary endpoint was percentage time in a high ratio range (≥3:4) of plasma (PLAS):RBC and platelet (PLT):RBC over 6 h. Secondary endpoints included time to massive transfusion protocol activation, time to calcium and tranexamic acid (TXA) dosing, and cumulative 6-h ratios. Included patients (n = 772) were 35 (24-51) years old with an Injury Severity Score of 27 (17-38) and 42% had penetrating injuries. RT-PI (n = 10) patients spent 96% of the 6-h resuscitation in a high PLAS:RBC range, no different versus CONTROL (n = 87) (96%) but more than PROMMTT (n = 675) (25%, p < .001). In the MT+ subgroup, optimal PLAS:RBC and PLT:RBC were maintained for the entire 6 h in RT-PI (n = 4) versus PROMMTT (n = 391) patients for both PLAS (p < .001) and PLT ratios (p < .001). Time to TXA also improved significantly in RT-PI versus CONTROL patients (27 min [22-31] vs. 51 min [29-98], p = .035). In this prospective study, RT-PI was associated with optimized DCR. Multicenter validation of this novel approach to optimizing DCR implementation is warranted.

Strengthening the energy efficiency ratio of warm deep gas-assisted hydrate production through optimizing water circulation

Utilizing the geothermal energy from the deep gas layer to enhance the hydrate decomposition is a potential clean production approach, avoiding the vast costs and severe pollution in the traditional heat injection scheme. In this work, a novel method was proposed to promote hydrate decomposition by employing circulating water to transport heat from the deep gas layer. Results showed that increasing the water flow rate from 9.82 mL/min to 39.28 mL/min could significantly improve the production efficiency by 27.27 %. Yet, the energy efficiency ratio (EER) slightly decreased by 3.31 % due to the increased power consumption of the water pump. A hybrid water flow rate was thus used with a lower rate in the later production stage when the heat absorption of hydrate decomposition was declining accordingly. This was found to successively improve the EER by 2.68 % while maintaining comparable production efficiency; a further cycling regulation (intermittent circulating) of the hybrid water flow rate could significantly enhance the EER by 16.23 %. The results could guide the efficient utilization of natural geothermal energy to facilitate the large-scale gas production from the natural gas hydrates when heat supply from the surrounding sediments was limited.

Multilateral evaluation of the effects of utilizing thorium oxide in the Bushehr VVER-1000 reactor

Abstract The use of thorium oxide in thermal reactors is currently being explored due to its promising outcomes. One primary concern is how to reduce the pollution of core components and nuclear waste. The inclusion of 232Th in the reactor leads to the production of 233U and decreases the formation of minor actinides. On the other hand, 238U increases the production of 239Pu, a toxic and strategically significant isotope, along with minor actinides. Therefore, the potential of thorium to reduce the production of 239Pu, one of the most harmful isotopes, can be assessed in the Bushehr VVER-1000 reactor. This study involved replacing some uranium in the Bushehr VVER-1000 reactor with 232Th. The research focused on examining the environmental impact of nuclear waste, including activity, chain reactions, and isotope levels, over a two-year period. The impact of the new fuel substitution was evaluated in the Bushehr reactor, which has a power of 3,000 MWth, in three scenarios: thorium addition to 1.6 % enriched assemblies, thorium addition to 2.4 % enriched assemblies, and thorium addition to 3.6 % enriched assemblies. These changes were analyzed in terms of nuclear waste contamination, plutonium production, fuel burn-up, and conversion ratio, and compared to the reactor using UO2 fuel. The simulation was conducted using the MCNPX 2.6.0 computational code and heterogeneous geometry. The results indicate that nuclear waste pollution decreased when thorium was added to the 1.6 % and 2.4 % enriched assemblies, but increased when added to the 3.6 % assemblies. Additionally, fuel burn-up increased with the addition of thorium in the 1.6 % and 2.4 % assemblies, but decreased in the 3.6 % assemblies. However, the conversion ratio increased in all cases. The fuel temperature coefficient (FTC), moderator temperature coefficient (MTC), and void coefficient (VC) were calculated and evaluated.

Dynamic Cation Enrichment during Pulsed CO2 Electrolysis and the Cation-Promoted Multicarbon Formation.

Recently, pulsed electrolysis has been demonstrated as an emerging electrochemical technique that significantly promotes the performance of various electrocatalysis applications. The ionic nature of aqueous electrolytes implies a likely change in ionic distribution under these alternating potential conditions. However, despite the well-known importance of cations, the impact of pulsed electrolysis on the cation distribution remains unexplored as well as its influences on the performance. Herein, we explore the cation effects on the pulsed electrochemical CO2 reduction (p-CO2RR) using the most widely utilized alkali metal cations, including Li+, Na+, K+, and Cs+. It is discovered that the nature of cations can significantly influence the product ratio of C2+ over C1 (mostly CH4) during p-CO2RR in an order of Li+< Na+< K+< Cs+, much more profoundly than those of static cases. We report direct experimental evidence for the cation enrichment caused by pulsed electrolysis, depending on the radius of the hydrated ions. With further quasi-in situ analysis of the catalyst surface, the cation-promoted Cu dissolution-and-redeposition process was identified; this is found to alter the surface CuxO/Cu ratio during the pulsed process. We demonstrate that both the cation enrichment and the cation-adjusted surface CuxO/Cu composition impact the C2+/C1 ratio through the control of the surface-adsorbed CO population. These results reveal the presence of pulse-induced cation redistribution in emerging pulsed electrolysis techniques and provide a comprehensive understanding of alkali metal cation effects for improving the selectivity of p-CO2RR.

Does energy innovation heterogeneously affect renewable energy production?

Achieving long-term sustainable development is a critical global imperative, and the adoption of renewable energy sources plays a pivotal role in this endeavor, aided by the advancements of the Fourth Industrial Revolution. As a result, energy innovation has emerged as a crucial factor in realizing sustainable development goals. This study utilizes panel quantile regression analysis to investigate the relationship between energy innovation and renewable energy production in the Middle East and North Africa (MENA) region from 1985 to 2019. The findings suggest that energy innovation can effectively enhance renewable energy production, particularly in countries with higher proportions of renewable energy generation, such as Egypt, Morocco, and Tunisia. However, countries like Saudi Arabia, which have lower ratios of renewable energy production, may not experience a significant impact from energy innovation. Consequently, the study recommends implementing systematic and integrated measures that focus on raising awareness and improving conditions for the adoption of renewable energy. These measures can drive the transition towards a more sustainable energy landscape in the MENA region. Policymakers should prioritize research and development investment and incentives in countries with higher levels of renewable energy generation, while simultaneously addressing barriers and fostering knowledge sharing between countries with differing levels of renewable energy production.

The biological and preformed carbon pumps in perpetually slower and warmer oceans

Abstract. The marine carbon cycle is vitally important for climate and the fertility of the oceans. However, predictions of future biogeochemistry are challenging because a myriad of processes need parameterization and the future evolution of the physical ocean state is uncertain. Here, we embed a data-constrained model of the carbon cycle in slower and warmer ocean states as simulated under the RCP4.5 and RCP8.5 (RCP: Representative Concentration Pathway) scenarios for the 2090s and frozen in time for perpetuity. Focusing on steady-state changes from preindustrial conditions allows us to capture the response of the system integrated over all the timescales of the steady-state biogeochemistry, as opposed to typical transient simulations that capture only sub-centennial timescales. We find that biological production experiences only modest declines (of 8 %–12 %) because the reduced nutrient supply due to a more sluggish circulation and strongly shoaled mixed layers is counteracted by warming-stimulated growth. Organic-matter export declines by 15 %–25 % due to reductions in both biological production and export ratios, the latter being driven by warming-accelerated shallow respiration and reduced subduction of dissolved organic matter. The perpetual-2090s biological pump cycles a 30 %–70 % larger regenerated inventory accumulated over longer sequestration times, while preformed DIC is shunted away from biological utilization to outgassing. The regenerated and preformed DIC inventories both increase by a similar magnitude. We develop a conceptually new partitioning of preformed DIC to quantify the ocean's preformed carbon pump and its changes. Near-surface paths of preformed DIC are more important in the slower circulations, as weakened ventilation isolates the deep ocean. Thus, while regenerated DIC cycling becomes slower, preformed DIC cycling speeds up.