Science Advances
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2025
·Vol. 11
·期 5
·
IF 12.5
Zhuodong Tang,Jingyu Wu,Shaojun Wu,Wenjing Tang,Jian-Rong Zhang,Wenlei Zhu,Jun-Jie Zhu,Zixuan Chen
Enzymes facilitate the conversion of chemical energy into mechanical work during biochemical reactions, thereby regulating the dynamic metabolic activity of living systems. However, directly observing the energy release facilitated by fluctuating individual enzymes remains a challenge, leading to a contentious debate regarding the underlying reasons for this phenomenon. Here, we aim to overcome this challenge by developing an oscillating nanomotor powered by a single-molecule enzyme, which allows real-time tracking of energy transduction in enzymatic reactions. Through analysis of the shifts in free energy profiles within the nanomotors, our results unveil not only the heterogeneous energy release patterns of individual enzyme molecules but also the dynamic disorder of a particular enzyme in energy release over extended monitoring periods. By exploring six distinct types of single-molecule enzymatic reactions, we provide the direct evidence supporting the argument that the reaction enthalpy governs the enzymatic energy release. This approach has implications for understanding the mechanism of enzymatic catalysis and developing highly efficient nanomotors.
研究领域:
生物化学
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纳米技术
·
酶学
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DOI
PubMed
高影响因子
ORGANIC PROCESS RESEARCH & DEVELOPMENT
·
2022
·
IF 3.858
Mengbo Zhang,Yirong Feng,Linjin Lou,Haomiao Zhang,Jingdai Wang,Yongrong Yang
We present a flow strategy to characterize reaction enthalpy and showcase the application in synthesis of alkylaluminoxanes from the fast and exothermic alkylaluminum hydrolysis. Our platform mainly encompasses a three-dimensional printed micromixer and a tubular reactor in an adiabatic vacuum box, aided by a thermal imaging camera to record temperature profiles. The temperature increase at steady state is used to calculate the released heat, which is further decoupled to quantify the reaction enthalpy and enthalpy of mixing. We validate the concept with the classic neutralization reaction between sulfuric acid and sodium hydroxide, with less than 2% deviation from theoretical values. In application, we determine the exothermic reaction enthalpy and the endothermic enthalpy of mixing to be −143.13 and +7.66 kJ/mol for triisobutylaluminum hydrolysis and −164.63 and +5.03 kJ/mol for trimethylaluminum hydrolysis, respectively. The presented platform, on the one hand, yields new insights into the microreactor scale-up for alkylaluminoxane synthesis and, on the other hand, can be readily used to measure reaction enthalpies of other reactions.
研究领域:
化学工程
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材料科学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 20
·9723-9732
·
IF 8.867
Jiaguang Zheng,Xuezhang Xiao,Liuting Zhang,Shouquan Li,Hongwei Ge,Lixin Chen
A remarkable improvement in the hydrogen desorption performance of Mg(BH4)2–NaBH4 eutectic composite is achieved by simply ball-milling with fluorographene (FG). It is found that the desorption temperature of Mg(BH4)2–NaBH4 (∼200 °C) is still too high and liquid phase appears during dehydrogenation. Particularly, the novel bowl-like 3D Mg(BH4)2–NaBH4–FG composite can be formed after ball-milling. The novel Mg(BH4)2–NaBH4–FG exhibits a low dehydrogenation temperature of 114.9 °C with 6.9 wt% of pure hydrogen in seconds. In-depth investigations show that such greatly improved hydrogen desorption properties of the Mg(BH4)2–NaBH4–FG composite could be ascribed to both the “novel bowl-like 3D structure” with large specific surface area and the “reactant destabilized modification” owing to the decrease of the reaction enthalpy caused by the formation of NaMgF3. This finding provides a facile preparation of complex borohydride composites with low dehydrogenation temperature and fast rate, which accelerates its practical application in fuel cells.
研究领域:
材料科学
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氢能存储
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纳米技术
✓ 已验证
DOI
高影响因子
APPLIED ENERGY
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2018
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IF 7.9
Sen Liu,Hongxia Gao,Chuan He,Zhiwu Liang
In this work, a novel method in terms of reaction energy was proposed to evaluate the potential amine absorbents for post-combustion CO 2 capture, including two key parameters, i.e. the molar Gibbs energy change (Δ r G m ) of proton combination with amine and the molar reaction enthalpy (Δ r H m ) of protonated amine dissociation into amine and proton, which are calculated by the Van’t Hoff equation. Firstly, the equilibrium acid dissociation constant ( K a ) of seven primary and secondary amines were experimentally determined at 293–323 K. The calculated Δ r G m and Δ r H m values obtained by the novel method indicated that the 2-(ethylamino)ethanol (EAE) and 2-(methylamino)ethanol (MAE) were the alternative promising absorbents among the seven tested amines, with a relatively low Δ r G m of about −57.0 kJ/mol and Δ r H m of 49.7 kJ/mol. In addition, seven amine solutions with molar concentration of 2.5 M and 5.0 M were investigated by the rate-based fast screening method to validate the reliability and applicability of the novel method. The comprehensive comparison of the absorption rate, desorption rate, CO 2 equilibrium solubility and cyclic capacity, also demonstrated the same conclusion that EAE and MAE solutions presented good CO 2 capture performances. The 2.5 M and 5.0 M EAE solutions obtain the highest energy efficiency for CO 2 capture with the highest cyclic capacity, which is about 52.9% and 32.3% higher than those of Monoethanolamine (MEA) solution, respectively. Additionally, the structure-activity analysis of seven amines suggested that the addition of hydroxyl group can obviously decrease the absorption rate and energy consumption of amine solution for CO 2 removal, the alkyl group addition on or close to amino group with steric hindrance is favorable for the CO 2 capture performance, while the addition of methyl group on amine molecular without steric hindrance can reduce the CO 2 cyclic capacity. What’s more, four tertiary amines were also investigated by using these two approaches, and the compared results further validated the accuracy and applicability of the proposed novel method.
研究领域:
化学工程
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环境科学
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DOI
高影响因子
BULLETIN OF THE KOREAN CHEMICAL SOCIETY
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2017
·Vol. 38
·期 3
·369-377
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IF 0.602
Fei Shi,Guo Bing Li,Hong Liang Sun,Wang Feng Cai
The dihydric alcohol transesterification of 1,4-butanediol with methyl acetate catalyzed by the ion-exchange resin is researched. The chemical system involves two transesterification reactions in series, with 1,4-butanediol monoacetate as an intermediate product. The effects of the catalyst type, catalyst size, catalyst loading, stirrer speed, the initial reactant ratio, and the reactive temperature have been meticulously studied. The results show that this consecutive transesterification is exothermic and the experimental values of reaction enthalpy are −8.50 and −6.85 kJ/mol, which are in good agreement with the values computed from the standard formation enthalpy. Three kinetic models (PH, LH, and ER) are applied to correlate the experimental data, of which ER model gives the best result with the lowest mean relative error. The activation energies are calculated to be 38.53 and 51.06 kJ/mol by ER model, demonstrating that the overall reaction rates are controlled by the reaction on the catalyst surface.
研究领域:
化学工程
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催化反应
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2020
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IF 5.065
Lei Yuan,Hongshuai Gao,Haiyan Jiang,Shaojuan Zeng,Tao Li,Baozeng Ren,Xiangping Zhang
A novel type of dual-functionalized pyridinium-based ionic liquids (ILs) with acidic protons and hydroxyl groups , were designed and synthesized for ammonia (NH 3 ) absorption. The NH 3 absorption isotherms in dual-functionalized pyridinium-based ILs at temperatures from 303.15 to 343.15 K and pressures up to 600 kPa were computed using gas-liquid equilibrium method. It revealed that 4-pyridinemethanol bis(trifluoromethane)sulfonamide [4-MeOHPy][NTf 2 ] showed the maximum NH 3 solubility of 3.43 mol NH 3 /mol IL at 313.15 K and atmospheric pressure, surpassing any nonmetallic ILs previously reported. Furthermore, the characteristics of isotherms under low pressures behaved an obvious chemical reaction between ILs and NH 3 , and all experimental solubilities were regulated by a reaction equilibrium thermodynamic model (RETM). The thermodynamic properties were further obtained to better understand the NH 3 absorption process. The results indicated that this model endorses the 1:1 (NH 3 -IL) mole ratio of chemical reaction mechanism and the reaction enthalpy is main driving force of NH 3 absorption in ILs.
研究领域:
化学工程
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物理化学
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DOI
高影响因子
JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
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2021
·
IF 3.66
Qiang Chen,Yuqing Ni,Jun Liang,Lei Ni,Juncheng Jiang,Yong Pan,Qingsheng Wang
Esterification reactions between anhydrides and alcohols catalyzed by sulfuric acid have broad applications in the food, cosmetic, and pharmaceutical industries. However, the exothermic behavior cannot be well explained, especially in semibatch reactors with different feeding procedures. In this study, a series of esterification processes in semibatch systems were conducted with a wide range of feeding rates with two different substrates. The structures of initial catalytic substrates were characterized using in situ Fourier Transform Infrared (FTIR) spectroscopy. A total of 11 reaction pathways, including those for the initial activation of substrates and the subsequent reactions of the feeding process, were calculated by the density functional theory (DFT) method. Three possible catalytic cycles of the esterification with specific acid catalysis, protonated intermediate, and protonated intermediate and H 2 O, were established for the semibatch esterification reaction based on calculated results and experimental evidence. Thermal safety parameters such as reaction enthalpy ( Δ H r ), adiabatic temperature rise ( Δ T r , a d ), and maximum temperature of the synthetic reaction (MTSR) were determined based on Wilson equation used to calibrate mixing heat. The results reveal that mixing heat was 2.5 kJ/mol with same mole ratio of n -butanol ( n B) and propionic anhydride (PA). The reactions started by PA are dominant, no matter whether the substrate is n B or PA. The initial reaction rate is restricted by the low concentration of catalyst and active reactant when n B is used as substrate, which lead to significant reactant accumulation with high MTSR of approximately 160 °C. Furthermore, feeding n B into PA allows a controllable increase in the Δ T r , a d realized by changing the feeding rate and limiting the accumulation of reactant.
研究领域:
化学工程
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物理化学
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过程安全
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产品关联
DOI
高影响因子
ENERGY & FUELS
·
2017
·
IF 3.091
Yongli Sun,Yanling Zhang,Luhong Zhang,Bin Jiang,Wenhao Gu,Huawei Yang
In this work, a kind of aqueous solution of novel protic triamine-based ionic liquid was proposed for efficient SO2 capture. The mixed absorbents were prepared by blending 1,1,4,7,7-pentaethyldiethylene (PEDETA) with sulfuric acid and water, and their physicochemical properties were studied by various methods. Remarkably, the viscosities of the mixed absorbents are in the range of 1.44–1.85 mPa s at 293.2 K, which is as low as water. Detailed SO2 absorption experiments were carried out to investigate the influence of some important factors, including temperature (298.2, 313.2, and 328.2 K), SO2 partial pressure (0–1 bar), and sulfuric acid proportion. It is worth noting that the mixed absorbents showed excellent absorption capacity, especially at a low partial pressure. All absorbed SO2 could be released easily and completely by the method of heating reflux. More importantly, the absorbent could be reused for at least 5 cycles without noticeable changes in both absorption performance and chemical structure. A thermogravimetric analysis further confirmed its good thermal stability. The detailed absorption mechanism was proposed and demonstrated by an infrared spectrum. In the end, the pKa values and reaction enthalpy of the protonation reaction of PEDETA were determined by acid titration and parameter analysis based on the reaction equilibrium model. In summary, the mixed absorbents, which possess low viscosities, good resistance to sulfuric acid, excellent capacity, and reusability, may have a good perspective in industrial SO2 capture.
研究领域:
环境科学
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化学工程
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材料科学
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DOI
高影响因子
JOURNAL OF FOOD BIOCHEMISTRY
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2022
·Vol. 46
·期 8
·e14192
·
IF 3.654
Hongan Li,Chengyue Zhang,Zeyuan Deng,Bing Zhang,Hongyan Li
The quantum chemical density functional theory and in vitro chemical-based antioxidant assays were used to research the reaction mechanism of delphinidin/pelargonidin with free radicals including superoxide anion radicals (O 2 − ∙) and hydroperoxide radicals (OOH∙). The geometric configuration, bond dissociation energy, PCM (polarizable continuum model) solvent model reaction enthalpy changes were studied to explain the transition states, and the reaction enthalpy change value was calculated to determine the active site. From the results of spatial configuration, delphinidin showed a stronger conjugation effect than that of pelargonidin. The dihedral angle between the three rings of delphinidin was almost 180°, and the angle between the B and C rings was only −2.81868°. Both coplanar and antioxidant activity of delphinidin was better than pelargonidin. The consequences of reaction enthalpy change in PCM were consistent with the bond dissociation energy. The phenolic hydroxyl bond dissociation energy of delphinidin was slightly smaller than that of pelargonidin. Moreover, the C4' site of delphinidin and the C3 site of pelargonidin were the active sites for scavenging free radicals. The free radical scavenging ability of delphinidin was marginally higher than that of pelargonidin. On the other hand, in vitro antioxidant results proved the scavenging ability of delphinidin and pelargonidin on superoxide anions, DPPH, and ABTS ∙+ free radicals. It was shown that the chemical-based antioxidant activity was consistent with the theoretical calculation results, with delphinidin showing greater antioxidant activity. These results could explain the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals from chemical reactions. Practical applications This manuscript explained the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals through the analysis of the geometric configuration of delphinidin/pelargonidin and the theoretical calculation of the reaction transition state. It could also speculate on the possible reaction sites, and provide a basis for judging how to efficiently select antioxidants with great antioxidant activity.
研究领域:
化学
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生物化学
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分子生物学
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药理学
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产品关联
DOI
PubMed
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2023
·
IF 7.8
Hang Yao,Lei Ni,Yinshan Liu,Gang Fu,Juncheng Jiang,Zhen Cheng,Yuqing Ni,Zhiquan Chen
The exothermic pattern of m-xylene nitration with mixed acid in semi-batch mode was studied by reaction calorimetry . Adiabatic temperature rise ( Δ T ad ) and reaction enthalpy ( ∆ H ) were obtained to identify the thermal hazard. Process conditions including stirring rate, reaction temperature and strength of mixed acid were studied to optimize the reaction. Optimal yield (95.5%) was reached under the conditions of sufficient stirring rate, 70% strength of mixed acid and reaction temperature of 40 °C. Meanwhile, the thermal stability of nitration products was investigated by differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). Pyrolysis kinetic parameters were calculated under non-isothermal and adiabatic conditions . Furthermore, the maximum temperature of the runaway system for synthesis reaction ( MTSR ) was determined to analyze the reaction hazard. The thermal risk of nitration of m-xylene was also assessed by the risk matrix and Stoessel criticality diagram. In addition, the nitration mechanism of m-xylene was presented. The active site for the electrophilic reaction of m-xylene was predicted via theoretical approach which was in consistent with the selectivity obtained by the experiment. These findings provide guidance for the safe operation of m-xylene nitration and can be used for further scale-up.
研究领域:
化工工程
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热安全
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过程优化
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反应动力学
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风险评估
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）