| 1. |
- Guo, Sihua, et al.
(författare)
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Toward ultrahigh thermal conductivity graphene films
- 2023
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- With increasing demands of high-performance and functionality, electronics devices generate a great amount of heat. Thus, efficient heat dissipation is crucially needed. Owing to its extremely good thermal conductivity, graphene is an interesting candidate for this purpose. In this paper, a two-step temperature-annealing process to fabricate ultrahigh thermal conductive graphene assembled films (GFs) is proposed. The thermal conductivity of the obtained GFs was as high as 3826 +/- 47 W m(-1) K-1. Extending the time of high-temperature annealing significantly improved the thermal performance of the GF. Structural analyses confirmed that the high thermal conductivity is caused by the large grain size, defect-free stacking, and high flatness, which are beneficial for phonon transmission in the carbon lattice. The turbostratic stacking degree decreased with increasing heat treatment time. However, the increase in the grain size after long heat treatment had a more pronounced effect on the phonon transfer of the GF than that of turbostratic stacking. The developed GFs show great potential for efficient thermal management in electronics devices.
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| 2. |
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| 3. |
- Li, Qishuang, et al.
(författare)
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Identification of the cytochrome P450s responsible for the biosynthesis of two types of aporphine alkaloids and their de novo biosynthesis in yeast
- 2024
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Ingår i: Journal of Integrative Plant Biology. - 1672-9072 .- 1744-7909. ; 66:8, s. 1703-1717
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Tidskriftsartikel (refereegranskat)abstract
- Aporphine alkaloids have diverse pharmacological activities; however, our understanding of their biosynthesis is relatively limited. Previous studies have classified aporphine alkaloids into two categories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each category. In this study, we identified two specific cytochrome P450 enzymes (CYP80G6 and CYP80Q5) with distinct activities toward (S)-configured and (R)-configured substrates from the herbaceous perennial vine Stephania tetrandra, shedding light on the biosynthetic mechanisms and stereochemical features of these two aporphine alkaloid categories. Additionally, we characterized two CYP719C enzymes (CYP719C3 and CYP719C4) that catalyzed the formation of the methylenedioxy bridge, an essential pharmacophoric group, on the A- and D-rings, respectively, of aporphine alkaloids. Leveraging the functional characterization of these crucial cytochrome P450 enzymes, we reconstructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast (Saccharomyces cerevisiae) for the de novo production of compounds such as (R)-glaziovine, (S)-glaziovine, and magnoflorine. This study provides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.
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| 4. |
- Aryal, Nabin, et al.
(författare)
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Microbial electrochemical approaches of carbon dioxide utilization for biogas upgrading
- 2022
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 291:Part 1
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Tidskriftsartikel (refereegranskat)abstract
- Microbial electrochemical approach is an emerging technology for biogas upgrading through carbon dioxide (CO2) reduction and biomethane (or value-added products) production. There are limited literature critically reviewing the latest scientific development on the Bioelectrochemical (BES) based biogas upgrading technology, including CO2 reduction efficiency, methane (CH4) yields, reactor operating conditions, and electrode material tested in BES reactor. This review analyzes the reported performance and identifies the crucial parameters to be considered for future optimization, which is currently missing. In this review, the performances of BES approach of biogas upgrading under various operating settings in particular fed-batch, continuous mode in connection to the microbial dynamics and cathode materials have been thoroughly scrutinized and discussed. Additionally, other versatile application options associated with BES based biogas upgrading, such as resource recovery, are presented. The three-dimensional electrode materials have shown superior performance in supplying the electrons for the reduction of CO2 to CH4. Most of the studies on the biogas upgrading process conclude hydrogen (H2) mediated electron transfer mechanism in BES biogas upgrading.
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| 5. |
- Chen, Huang, et al.
(författare)
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A portable micro glucose sensor based on copper-based nanocomposite structure
- 2019
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1369-9261 .- 1144-0546. ; 43:20, s. 7806-7813
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Tidskriftsartikel (refereegranskat)abstract
- Precisely detecting the concentration of glucose in the human body is an attractive way to prevent or treat diabetes. Portable glucose sensors with non-enzymatic catalytic materials have received great attention in recent years. Herein, a facile strategy for fabricating a high-performance electrochemical sensor is proposed. A non-enzymatic three-electrode integrated glucose sensor device based on CuO nano-coral arrays/nanoporous Cu (NCA/NPC) is designed and fabricated. The portable NCA/NPC glucose sensor device exhibits high catalytic activity for glucose. The great performance of the NCA/NPC glucose sensor device derives from the excellent conductivity of the NPC substrate and the high electrocatalytic activity of CuO nano-coral arrays. This device exhibits a high sensitivity of 1621 μA mM -1 cm -2 in the linear range of 0.0005-5.0 mM, low detection limit of 200 nM (S/N = 3), fast response time of 3 s, good anti-interference performance, excellent repeatability and considerable stability for glucose detection. This work will certainly provide an efficient structure and proper catalytic material choices for future non-enzymatic glucose sensors.
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| 6. |
- Chen, S., et al.
(författare)
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An overview of carbon nanotubes based interconnects for microelectronic packaging
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 113-119
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Konferensbidrag (refereegranskat)abstract
- Owing to the great demand in more functions and miniaturization in microelectronic packaging, the dimensions of interconnects has decreased extremely, which has resulted in electrical, thermal, and mechanical reliability issues. To address these issues, carbon nanotube (CNT) has been selected as a promising alternative material for the interconnects in packaging due to its large current density, high thermal conductivity, great flexibility, and low coefficient of thermal expansion (CTE). In this paper, the development of CNTs based vertical interconnects was reviewed. However, the resistivity of CNTs based interconnects was much higher than that of copper interconnects. Thus, this review focused on the resistivity of CNTs-based interconnects in different fabrication process and pointed out what improves the resistivity. In the future, CNTs-Cu nanocomposite with unique properties could be the suitable material for bumps to reduce the resistivity of CNTs based bumps further.
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| 7. |
- Chen, Yifeng
(författare)
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CO2 separation using ionic liquid-based absorbents : thermodynamics and kinetics
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ionic liquids (ILs) have shown great potential to be used as absorbents for CO2 separation owing to their unique properties such as immeasurably low vapour pressure, high thermal stability, high CO2 affinity, and tunable structure. A huge amount of researches have been carried out, and most of them focused on developing novel ILs for CO2 separation. However, high viscosity will impede the IL-based absorbents for the large-scale applications in CO2 separation.The goal of this thesis was to develop IL-based hybrid green absorbents (i.e. choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/H2O ([Cho][Pro]/PEG200/H2O) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide /PEG200 ([Hmim][Tf2N]/TiO2/PEG200)) for CO2 separation, in which H2O and/or PEG200 were used as co-solvents to adjust the viscosity. A systematic study was conducted from pure to multi-component systems convering experimental measurements and theoretical modeling of thermdynmaics and kinetics, and thus the effects of co-solvents on properties, phase equilibria, and kinetics were also analyzed.To provide reliable and systematic properties and study the effect of H2O, the properties of PEG200 and PEG200/H2O were surveyed, evaluated, and correlated. The density and viscosity of [Cho][Pro]/PEG200/H2O were measured and correlated, and the excess mole volume and excess Gibbs energy of activation were estimated to understand the molecular structure and interactions between [Cho][Pro]/PEG200 and H2O. The results showed that H2O and PEG200 could decrease the viscosity of the hybrid absorbent significantly, and H2O interacted strongly with [Cho][Pro]/PEG200.To obtain reliable and systematic gas solibilities and analyze the effect of H2O, the solubilities of pure CO2, CH4, and N2 in PEG200 were surveyed, measured, evaluated, and described with theoretical models. The CO2, CH4, and N2 solubilities in PEG200/H2O were measured and described with the Redlich-Kwong Nonrandom-Two-Liquid (RK-NRTL) model. The CO2 solubilities in [Cho][Pro]/PEG200 and [Cho][Pro]/H2O were also surveyed, measured, evaluated, and described using the RK-NRTL model. Furthermore, CO2 solubility in the hybrid absorbent was predicted with the model and compared with the new experimental results. The further investigation showed that the formation of carbomate dominated the entire CO2 absorption process by [Cho][Pro]/PEG200/H2O, and the presence of H2O resulted in the formation of bicarbonate.To study the kinetics systematically combined with the effect of H2O, the liquid-side mass-transfer coefficients (kL) of [Cho][Pro]/PEG200/H2O were obtained from the CO2 diffusion coefficients () and the kL values in PEG200/H2O, in which was calculated from the density and viscosity of the hybrid absorbents, while the kL values in PEG200/H2O were measured experimentally. The reaction rate constant of CO2 in the hybrid absorbents was also estimated.Based on the systematic studies from experimental measurement and modeling, it showed that 30 wt%[Cho][Pro]/H2O + PEG200 could be promising for CO2 separation with the consideration of both thermodynamic and kinetic properties. In addition, the hybrid absorbent also showed the good recyclability.To use the confinement as the other strategy for further developing IL-based technology, the CO2 solubility in [Hmim][Tf2N]/TiO2/PEG200 with different ratios of [Hmim][Tf2N]/TiO2 was measured, and the Henry’s constant and absorption enthalpy of CO2 in the hybrid absorbent were calculated. The CO2 solubility in the hybrid absorbent was described with the Henry's law, the contribution of the confinement effect on the CO2 solubility was quantified, and the relationship between the roughness of TiO2 and molecular parameters was established. The results showed that the mass ratio of [Hmim][NTf2]/TiO2 in the hybrid absorbent should be lower than 5.72 %, where the contribution of confinement occupied around 20 % of the total CO2 absorption capacity in [Hmim][NTf2]/T500/PEG200. 2.88 wt%[Hmim][NTf2]/T500 + PEG200 could be promising for CO2 separation on aspects of CO2 capacity and absorption enthplay, and further study will be conducted on the properties and CO2 absorption kinetics.
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| 8. |
- Chen, Yifeng, et al.
(författare)
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CO2 absorption using a hybrid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/polyethylene glycol absorbent
- 2021
-
Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 538
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Tidskriftsartikel (refereegranskat)abstract
- Developing novel hybrid ionic liquid/porous material/co-solvent absorbents with the confinement effect is essential for CO2 separation. In this study, CO2 solubilities in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/polyethylene glycol ([Hmim][Tf2N]/TiO2-PEG200) with different ratios of [Hmim][Tf2N]/TiO2 and various roughnesses of TiO2 (P25 and T500) were measured and described with the Henry's law. Furthermore, the contribution of the confinement effect on the CO2 solubility was quantified, and the relationship between the surface roughness and molecular parameters was established for predicting its contribution to the confinement effect. In addition, the hybrid absorbent was recycled by a multi-cycle experiment. The results show that the contribution of confinement effect on CO2 absorption capacity (on mass basis) and Gibbs free energy occupy around 24.5 % and 8.12 % in [Hmim][NTf2]/T500-PEG200 (w[Hmim][NTf2]/T500 = 2.88 wt%) at 308.2 K, respectively. The surface roughness can double the confinement effect. Based on the CO2 absorption capacity and enthalpy, [Hmim][NTf2]/T500-PEG200 (w[Hmim][NTf2]/T500 = 2.88 wt%) is a promising hybrid absorbent for CO2 separation.
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| 9. |
- Chen, Yifeng, et al.
(författare)
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CO2 separation using a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent
- 2020
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 257
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Tidskriftsartikel (refereegranskat)abstract
- Developing novel hybrid absorbents is essential for CO2 separation. In this study, the density and viscosity of a hybrid absorbent (choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were measured experimentally, and its CO2 solubility was also determined. The excess mole volume and excess Gibbs energy of activation of the hybrid absorbent were further estimated to understand the molecular structure and interactions between [Cho][Pro]/PEG200 and H2O. The CO2 solubilities in [Cho][Pro]/PEG200 and [Cho][Pro]/H2O were analyzed and described using the Redlich–Kwong non-random-two-liquid (RK-NRTL) model. Furthermore, the CO2 solubility in the hybrid absorbent was predicted using the RK-NRTL model and was compared with the new experimental results for verification. The effect of H2O on the CO2 absorption performance was further analyzed. The performance and cost of the hybrid absorbent were compared with those of other commercialized CO2 absorbents. In addition, the recyclability of the hybrid absorbent for CO2 separation was studied. The results of this study indicated that the hybrid absorbent could be promising for CO2 separation.
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| 10. |
- Chen, Yifeng, et al.
(författare)
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Developing aqueous porous carbons for biogas upgrading
- 2024
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Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 329
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Tidskriftsartikel (refereegranskat)abstract
- Developing novel sorbents is essential for biogas upgrading. In this study, mixed sorbents of aqueous porous carbons were developed to separate CO2 from the biogas, where the porous carbon with the developed micropore structure was identified as the most desirable constituent. Both thermodynamics and kinetics were studied experimentally, and Henry’s constant (KH) and the liquid-side mass-transfer coefficient (kL) of CO2 in the mixed sorbent as well as the selectivity of CO2/CH4 were obtained accordingly. Furthermore, the CO2 separation performance was evaluated with a proposed index, and the cost of biogas upgrading using the mixed sorbent was estimated and compared. The results showed that the porous carbon with the developed micropore structure led to better performance on KH and kL of CO2 in the mixed sorbent, and the mixed sorbent with 3.03 wt% porous carbon exhibited the best CO2 separation performance, reducing 36.2 % in cost compared to the current technologies.
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| 11. |
- Chen, Yifeng, et al.
(författare)
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Developing hybrid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/water absorbent for CO2 separation
- 2022
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 326
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Tidskriftsartikel (refereegranskat)abstract
- The development of novel absorbents is essential for improving CO2 separation technology. In this study, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/water ([Hmim][NTf2]/TiO2-H2O) was developed to separate CO2, where the thermodynamic and kinetic experiments were conducted, and Henry's constant and the liquid-side mass-transfer coefficient were determined accordingly. Furthermore, CO2 separation performance in a bubble tower was validated. A previously proposed index named “absorption ability” (AA) was used to predict and compare the experimental results. Additionally, the cost of biogas upgrading (i.e., CO2 removal for biogas purification) using [Hmim][NTf2]/TiO2-H2O was estimated. The results showed that for the developed [Hmim][NTf2]/TiO2-based technology, the average CO2 mass-transfer rate was increased by 20.0% compared with the current commercialized technology, and the contributions from the thermodynamic and kinetic aspects were 2.5% and 17.5%, respectively. The cost of biogas upgrading was 16.6% lower. In addition, AA successfully predicted the performance of CO2 separation technologies, achieving an average relative deviation of 8.1%.
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| 12. |
- Chen, Yifeng, et al.
(författare)
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Experimental characterization and micromechanical modeling of damage-induced permeability variation in Beishan granite
- 2014
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 71, s. 64-76
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Tidskriftsartikel (refereegranskat)abstract
- Triaxial compression tests with measurements of permeability were performed on core granite samples taken at 450-550 m depth from the Beishan area in Gansu Province, a potential site for China's high-level radioactive waste (HLW) disposal. Corresponding to the distinct features in the stress-strain behaviors, the permeability of the Beishan granite was found to evolve with a clear permeability decrease in the initial microcrack closure region, a constant permeability value in the elastic region and a dramatic permeability increase in the crack growth region. The permeability increases by up to and over two orders of magnitude as deviatoric stress increases up to sample failure; but at a given deviatoric stress, the permeability reduces remarkably with the increase of confining pressure. An empirical upper bound permeability model was presented by relating the mechanisms involved in the microstructure alteration to the permeability change, and the experimental results were well simulated by the proposed model. Combined with field geological characterization and numerical simulation, the implications of the experimental results for China's HLW disposal were discussed.
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| 13. |
- Chen, Yifeng, et al.
(författare)
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Kinetics study and performance comparison of CO2 separation using aqueous choline-amino acid solutions
- 2021
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Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic and kinetic properties of CO2 in aqueous choline-amino acids ([Cho][AA]s) are important information to demonstrate their performance. In this study, the apparent kinetic properties of CO2 in the five aqueous [Cho][AA]s, including the liquid-side mass-transfer coefficients, enhancement factor, and reaction rate constant, were systematically studied. Furthermore, a new ‘‘absorption ability’’ (AA) index was proposed, combining the apparent kinetic properties determined in this study and thermodynamic properties determined in our previous study. The CO2 separation performance using aqueous [Cho][AA]s was evaluated based on the AA and CO2 desorption enthalpy values. The results show that 30 wt% aqueous choline-serine is a promising absorbent for CO2 separation, and it is comparable to aqueous monoethanolamine.
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| 14. |
- Chen, Yifeng, et al.
(författare)
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Kinetics study and performance evaluation of a hybrid choline-glycine/polyethylene glycol/water absorbent for CO2 separation
- 2023
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Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 304
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic and kinetic properties of absorbents are beneficial in evaluating their CO2 separation performance. In this study, the kinetic properties of CO2 in a hybrid choline-glycine/polyethylene glycol/water absorbent, including the liquid-side mass-transfer coefficient, enhancement factor, and reaction rate constant, were systematically determined through experimental measurements and data processing. Furthermore, an index referred to as “absorbility” was proposed to combine the kinetic properties determined in this study with the thermodynamic properties obtained in our previous study to evaluate the CO2 separation performance. Additionally, the regeneration performance of the hybrid absorbent was also conducted. The results show that the performance of the hybrid absorbent (30 wt% [Cho][Gly] + 10 wt% PEG200 + 60 wt% H2O) is comparable to that of aqueous monoethanolamine, and is thus promising for CO2 separation, considering its low regeneration temperature and low environmental impact.
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| 15. |
- Chen, Yifeng, et al.
(författare)
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Mass-transfer kinetics of CO2 in a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent
- 2021
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 336
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mass-transfer kinetics of CO2 in novel hybrid absorbents with physical and chemical contributions is essential for process design and evaluation. In this study, the liquid-side mass-transfer coefficients (kL) and second-order reaction rate constants (k2) of CO2 in hybrid absorbents (namely, choline-2-pyrrolidine-carboxylic acid salt/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were determined. The kL values for the hybrid absorbents were obtained from the CO2 diffusion coefficients (DCO2) and the kL values in PEG200/H2O. The DCO2 value was calculated from the density and viscosity of the hybrid absorbents, whereas the kL values in PEG200/H2O were measured experimentally. The k2 values of CO2 in the hybrid absorbents were estimated according to the reaction mechanism, the enhancement factor, and the kL values, and compared with those of other commercialized absorbents. The results showed that 30 wt% [Cho][Pro]+70 wt% H2O had the highest kL and k2 values at atmospheric pressure, whereas the values of kL and k2 of CO2 in 30 wt% [Cho][Pro]/H2O+PEG200 were comparable to those in diethanolamine aqueous and amino-functionalized ILs. The hybrid absorbent of [Cho][Pro]/PEG200/H2O could be promising for CO2 separation considering its thermodynamic and kinetic properties.
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| 16. |
- Chen, Yifeng, et al.
(författare)
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Micromechanical Modeling of Anisotropic Damage-Induced Permeability Variation in Crystalline Rocks
- 2014
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer Science and Business Media LLC. - 0723-2632 .- 1434-453X. ; 47:5, s. 1775-1791
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study on the initiation and progress of anisotropic damage and its impact on the permeability variation of crystalline rocks of low porosity. This work was based on an existing micromechanical model considering the frictional sliding and dilatancy behaviors of microcracks and the recovery of degraded stiffness when the microcracks are closed. By virtue of an analytical ellipsoidal inclusion solution, lower bound estimates were formulated through a rigorous homogenization procedure for the damage-induced effective permeability of the microcracks-matrix system, and their predictive limitations were discussed with superconducting penny-shaped microcracks, in which the greatest lower bounds were obtained for each homogenization scheme. On this basis, an empirical upper bound estimation model was suggested to account for the influences of anisotropic damage growth, connectivity, frictional sliding, dilatancy, and normal stiffness recovery of closed microcracks, as well as tensile stress-induced microcrack opening on the permeability variation, with a small number of material parameters. The developed model was calibrated and validated by a series of existing laboratory triaxial compression tests with permeability measurements on crystalline rocks, and applied for characterizing the excavation-induced damage zone and permeability variation in the surrounding granitic rock of the TSX tunnel at the Atomic Energy of Canada Limited's (AECL) Underground Research Laboratory (URL) in Canada, with an acceptable agreement between the predicted and measured data.
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| 17. |
- Chen, Yifeng, et al.
(författare)
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Modeling coupled THM processes of geological porous media with multiphase flow : Theory and validation against laboratory and field scale experiments
- 2009
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Ingår i: Computers and geotechnics. - : Elsevier BV. - 0266-352X .- 1873-7633. ; 36:8, s. 1308-1329
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Tidskriftsartikel (refereegranskat)abstract
- A FEM model for analysis of fully coupled multiphase flow, thermal transport and stress/deformation in geological porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a three phase (solid-liquid-gas) system. Six processes (i.e. stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes) and their coupling effects are considered, which not only makes the problem well-defined, but renders the governing PDEs closed, complete. compact and compatible. Displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity are selected as basic unknowns. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling are modeled. As a result, the relative humidity and other related variables in porous media can be evaluated on a sounder physical basis. A three dimensional computer code, THYME3D, was developed, with eight degrees of freedom at each node. The laboratory CEA Mock-up test and the field scale FEBEX benchmark test on bentonite performance assessment for underground nuclear waste repositories were used to validate the numerical model and the software. The coupled THM behaviors of the bentonite barriers were satisfactorily simulated, and the effects and impacts of the governing equations, constitutive relations and property parameters on the coupled THM processes were understood in terms of more straightforward interpretation of physical processes at microscopic scale of the porous media. The work developed enables further in-depth research on fully coupled THM or THMC processes in porous media.
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| 18. |
- Chen, Yifeng, et al.
(författare)
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Novel Index to Screen and Evaluate Ionic Liquids for CO2/CH4 Separation
- 2024
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045.
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Tidskriftsartikel (refereegranskat)abstract
- Efficient CO2/CH4 separation for biogas upgrading can be achieved by using ionic liquids (ILs) as absorbents. In this study, a novel index named “relative absorption ability” (RAA) was proposed for the first time to facilitate the screening and evaluation of potential absorbents based on their thermodynamic and kinetic properties for CO2/CH4 separation. Subsequently, the properties of 2009 ILs were predicted with the conductor-like screening model, and the top 10 ILs were screened. Finally, the cost of the screened top two ILs for CO2/CH4 separation was further estimated with process simulation. The results further prove the reliability of the new proposed RAA index in screening and evaluating, and the screened promising ILs can reduce the costs of CO2/CH4 separation by 53.9% and 51.9%, respectively, in comparison to the current commercial technology.
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| 19. |
- Chen, Yifeng, et al.
(författare)
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Novel Solvent for CO2 Capture
- 2019
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 158, s. 5124-5129
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Tidskriftsartikel (refereegranskat)abstract
- To develop novel solvent for CO2 capture, CO2 absorption performance using the aqueous of polyethylene glycol 200 (PEG200) and choline-2-pyrrolidinecarboxylic acid ([Cho][Pro]) was studied and evaluated systematically in this work, in which the critical properties of PEG200 were estimated with group contribution method, and other thermo-physical properties were determined experimentally or taken from literatures directly and then correlated with empirical equations. The CO2 solubility in PEG200 was measured and represented with the Henry’s law and Poynting correction, while the measured CO2 solubility in PEG200/H2O was correlated with RK-NRTL model. [Cho][Pro] was used as the chemical ingredient to enhance the absorption capacity and rate of CO2 in [Cho][Pro]/PEG200/H2O, and the corresponding properties and CO2 solubility were studied. The kinetic parameters, such as enhancement factor (E), reaction rate constant (k), and activation energy (Ea) of CO2 in [Cho][Pro]/PEG200/H2O were estimated from the new experimental data measured in this work and compared with the commercialized aqueous MEA solution. The process simulation and pilot-testing based on [Cho][Pro]/PEG200/H2O will be performed in the future.
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| 20. |
- Chen, Yifeng, et al.
(författare)
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Thermodynamic Study for Gas Absorption in Choline-2-pyrrolidine-carboxylic Acid + Polyethylene Glycol
- 2016
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 61:10, s. 3428-3437
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of pure CO2, CH4, and N2 in the mixture of choline-2-pyrrolidine carboxylic acid ([Cho][Pro]) and polyethylene glycol (PEG200) (mass ratio = 1:2) was measured experimentally at temperatures from 308.15 to 338.15 K and pressures up to 28 bar, in which [Cho][Pro] is an ionic liquid and PEG200 is a cosolvent with the purpose to decrease the viscosity. It was found that [Cho][Pro]/PEG200 showed a good selectivity for CO2/CH4 and CO2/N2 separation. The measured experimental data points from this work and others were further used to estimate the thermodynamic properties including the Henry's law constants for the gases in [Cho][Pro]/PEG200, the equilibrium constant for the reaction between CO2 and [Cho][Pro], the CO2 absorption enthalpy in [Cho][Pro]/PEG200, and so forth. The consistent results of the CO2 absorption enthalpy at infinite dilution prove the reliability of the thermodynamic properties obtained in this work. The thermodynamic properties of [Cho][Pro]/PEG200 were further compared with other three typical absorbents, and the absorption enthalpy is nearly half of that for 30 wt % MEA aqueous solution. At the same time, the theoretical amount of absorbents needed for [Cho][Pro]/PEG200 is much lower than that of H2O scrubbing. This shows that [Cho][Pro]/PEG200 is a promising absorbent
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| 21. |
- Chen, Yifeng, et al.
(författare)
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Thermodynamic study on aqueous polyethylene glycol 200 solution and performance assessment for CO2 separation
- 2020
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 504
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Tidskriftsartikel (refereegranskat)abstract
- To develop polyethylene glycol 200 (PEG200) and aqueous PEG200 solutions (PEG200/H2O) as solvents for CO2 separation, in this study, the available thermo-physical properties of PEG200 and PEG200/H2O measured experimentally were surveyed, evaluated, and correlated with empirical equations. The solubility of CO2 in PEG200 was also surveyed, evaluated and described with the Henry's law with the Poynting correction, while the solubilities of CH4 and N2 in PEG200 were determined experimentally and then described with the Henry's law. The CO2, CH4 and N2 solubilities in PEG200/H2O were measured and described with the Redlich–Kwong Nonrandom-Two-Liquid (RK-NRTL) model. In addition, the performances of PEG200, PEG200/H2O and other commercialized physical solvents for CO2 separation were discussed based on the properties, and the biogas upgrading was chosen as the example to quantitatively evaluate the performances of PEG200 and PEG200/H2O with process simulation and compared with the high pressure water scrubbing (HPWS). It shows that the total energy usage and the amount of recirculated solvent for biogas upgrading can decrease by 9.1% and 26.5%, respectively, when H2O is replaced by PEG200 completely.
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| 22. |
- Dai, Zhengxing, et al.
(författare)
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Prediction and verification of heat capacities for pure ionic liquids
- 2021
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier. - 1004-9541 .- 2210-321X. ; 31, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- The heat capacity of ionic liquids is an important physical property, and experimental measuring is usually used as a common method to obtain them. Owing to the huge number of ionic liquids that can be potentially synthesized, it is desirable to acquire theoretical predictions. In this work, the Conductor-like Screening Model for Real Solvents (COSMO-RS) was used to predict the heat capacity of pure ionic liquids, and an intensive literature survey was conducted for providing a database to verify the prediction of COSMO-RS. The survey shows that the heat capacity is available for 117 ionic liquids at temperatures ranging 77.66-520 K since 2004, and the 4025 data points in total with the values from 76.37 to 1484 J·mol-1·K-1 have been reported. The prediction of heat capacity with COSMO-RS can only be conducted at two temperatures (298 and 323 K). The comparison with the experimental data proves the prediction reliability of COSMO-RS, and the average relative deviation (ARD) is 8.54%. Based on the predictions at two temperatures, a linear equation was obtained for each ionic liquid, and the heat capacities at other temperatures were then estimated via interpolation and extrapolation. The acquired heat capacities at other temperatures were then compared with the experimental data, and the ARD is only 9.50%. This evidences that the heat capacity of a pure ionic liquid follows a linear equation within the temperature range of study, and COSMO-RS can be used to predict the heat capacity of ionic liquids reliably.
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| 23. |
- Dai, Zhengxing, et al.
(författare)
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Screening ionic liquids for developing advanced immobilization technology for CO2 separation
- 2022
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Developing immobilized-ionic liquids (ILs) sorbents is important for CO2 separation, and prior theoretically screening ILs is desirable considering the huge number of ILs. In this study, the compressibility of ILs was proposed as a new and additional index for screening ILs, and the developed predictive theoretical model, i.e., electrolyte perturbed-chain statistical associating fluid theory, was used to predict the properties for a wide variety of ILs in a wide temperature and pressure range to provide systematic data. In screening, firstly, the isothermal compressibilities of 272 ILs were predicted at pressures ranging from 1 to 6,000 bar and temperatures ranging from 298.15 to 323.15 K, and then 30 ILs were initially screened. Subsequently, the CO2 absorption capacities in these 30 ILs at temperatures from 298.15 to 323.15 K and pressures up to 50 bar were predicted, and 7 ILs were identified. In addition, the CO2 desorption enthalpies in these 7 ILs were estimated for further consideration. The performance of one of the screened ILs was verified with the data determined experimentally, evidencing that the screen is reasonable, and the consideration of IL-compressibility is essential when screening ILs for the immobilized-IL sorbents.
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| 24. |
- Fan, Dong, et al.
(författare)
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Cardiovascular health profiles, systemic inflammation, and physical function in older adults : A population-based study
- 2023
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Ingår i: Archives of gerontology and geriatrics (Print). - : Elsevier BV. - 0167-4943 .- 1872-6976. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- We examined the association of modifiable cardiovascular health (CVH) metrics with physical function among rural older adults in China and the potential role of inflammatory mechanisms in the association. This study included 3733 stroke-and dementia-free participants (age >= 65 years; 56.9% women) in the baseline survey of a multimodal intervention study in rural China. From March-September 2018, data were collected via face-to-face interviews, clinical assessments, and laboratory tests. The Short Performance Physical Battery (SPPB) test was performed to assess physical function. We defined six modifiable CVH metrics according to the modified American Heart Association's recommendations. Serum interleukin (IL)-6 was measured in a subsample (n = 1156). Data were analyzed with multiple general linear and logistic regression models and structural equation modeling. Poor physical function (SPPB score <= 9) was defined in 1443 participants. Ideal CVH (vs. poor CVH) was associated with multivariable-adjusted odds ratio of 0.60 (95%CI 0.48-0.75) for poor physical function. Ideal CVH was significantly associated with higher scores on balance, chair stand, and walking speed tests (all p < 0.05). Moreover, ideal CVH profile was associated with lower serum IL-6 (multivariable-adjusted beta=-0.04; 95% CI-0.06,-0.01). Mediation analysis revealed that serum IL-6 accounted for 14% of the association of CVH with total SPPB score and 10% of the association with walking speed score (p < 0.05). This study suggests that an ideal CVH profile is associated with better physical function among stroke-and dementia-free older adults, partly via inflammatory mechanisms. The preventive implications of these findings warrant further investigation in cohort studies.
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| 25. |
- Fu, Yifeng, 1984, et al.
(författare)
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Graphene related materials for thermal management
- 2020
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Almost 15 years have gone ever since the discovery of graphene as a single atom layer. Numerous papers have been published to demonstrate its high electron mobility, excellent thermal and mechanical as well as optical properties. We have recently seen more and more applications towards using graphene in commercial products. This paper is an attempt to review and summarize the current status of the research of the thermal properties of graphene and other 2D based materials including the manufacturing and characterization techniques and their applications, especially in electronics and power modules. It is obvious from the review that graphene has penetrated the market and gets more and more applications in commercial electronics thermal management context. In the paper, we also made a critical analysis of how mature the manufacturing processes are; what are the accuracies and challenges with the various characterization techniques and what are the remaining questions and issues left before we see further more applications in this exciting and fascinating field.
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