In order to accurately understand the radial structural evolution of polyacrylonitrile (PAN) fibers in irradiation and heat treatment, trapezoidal scanning was performed on the fibers with synchrotron microfocus wide-angle X-ray scattering (μ-WAXS), and radial scanning with confocal Raman was used on the cross section of the fibers. The results indicate that PAN precursors and γ-irradiated/heated PAN fibers present a heterogeneous structure and share the same trend in terms of microstructure changes at different radial positions. The crystal size, crystallinity, and orientation of the (100) crystal plane in the skin layer of fibers are larger than that those in the core layer, and the d spacing of the (100) crystal plane in the skin layer of fibers is smaller than that present in the core layer. The difference is that γ-irradiated PAN fibers have no secondary crystallization in the core layer during heat treatment; this is because the strong penetration of γ irradiation can act on the core of the fibers. In addition, some tests including WAXS were employed to characterize the evolution of the crystalline structure, thermal properties, and chemical structure of the PAN fiber as a whole after irradiation and heat treatment. Combined with the analysis of regional structure evolution, the above results show that the irradiation treatment advances the inflection points of the crystal structures of PAN fibers in the skin and core layers during heat treatment, and the strong penetration of γ irradiation caused both to advance by a similar amount of time. The coupling of irradiation and heat treatment resulted in smaller differences between the skin and core layers of PAN preoxidized fibers in terms of d spacing, orientation, and graphitized structure.
为了准确了解聚丙烯腈（PAN）纤维在辐照和热处理过程中的径向结构演变，利用同步辐射微焦广角 X 射线散射（μ-WAXS）对纤维进行了梯形扫描，并利用共焦拉曼对纤维横截面进行了径向扫描。结果表明，PAN 前驱体和经γ辐照/加热的 PAN 纤维呈现异质结构，并且在不同径向位置的微观结构变化趋势相同。纤维表皮层（100）晶面的晶体尺寸、结晶度和取向均大于芯层，纤维表皮层（100）晶面的 d 间距小于芯层。所不同的是，经过γ辐照的 PAN 纤维在热处理过程中不会在芯层出现二次结晶；这是因为γ辐照的强穿透力可作用于纤维的芯部。此外，还采用了包括 WAXS 在内的一些测试来表征辐照和热处理后 PAN 纤维整体的结晶结构、热性能和化学结构的演变。结合区域结构演变分析，上述结果表明，在热处理过程中，辐照处理使 PAN 纤维表皮层和芯层的晶体结构拐点提前，γ 辐照的强穿透力使两者的拐点提前时间相近。辐照和热处理的耦合使 PAN 预氧化纤维的表皮层和芯层在 d 间距、取向和石墨化结构方面的差异较小。
{"title":"Synchrotron Microfocus Wide-Angle X-ray Scattering Reveals the Evolution of Radial Microstructural Heterogeneity in γ-Irradiated/Heated Polyacrylonitrile Fibers","authors":"Gaohui Wang, Ruiqi Shao, Feng Tian, Haiting Shi, Wei Wang, Hao Zhang, Tianyu Li, Xiuhong Li, Zhiwei Xu","doi":"10.1021/acs.jpcc.4c05196","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c05196","url":null,"abstract":"In order to accurately understand the radial structural evolution of polyacrylonitrile (PAN) fibers in irradiation and heat treatment, trapezoidal scanning was performed on the fibers with synchrotron microfocus wide-angle X-ray scattering (μ-WAXS), and radial scanning with confocal Raman was used on the cross section of the fibers. The results indicate that PAN precursors and γ-irradiated/heated PAN fibers present a heterogeneous structure and share the same trend in terms of microstructure changes at different radial positions. The crystal size, crystallinity, and orientation of the (100) crystal plane in the skin layer of fibers are larger than that those in the core layer, and the <i>d</i> spacing of the (100) crystal plane in the skin layer of fibers is smaller than that present in the core layer. The difference is that γ-irradiated PAN fibers have no secondary crystallization in the core layer during heat treatment; this is because the strong penetration of γ irradiation can act on the core of the fibers. In addition, some tests including WAXS were employed to characterize the evolution of the crystalline structure, thermal properties, and chemical structure of the PAN fiber as a whole after irradiation and heat treatment. Combined with the analysis of regional structure evolution, the above results show that the irradiation treatment advances the inflection points of the crystal structures of PAN fibers in the skin and core layers during heat treatment, and the strong penetration of γ irradiation caused both to advance by a similar amount of time. The coupling of irradiation and heat treatment resulted in smaller differences between the skin and core layers of PAN preoxidized fibers in terms of <i>d</i> spacing, orientation, and graphitized structure.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":null,"pages":null},"PeriodicalIF":4.126,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xingwen Pu, Zhangyi Fu, Yudong Yang, Di Wu, Pengchi Deng, Jingbo Lan
We herein disclose a highly efficient one-pot synthetic strategy for dihydrobenzo[a]fluorenes via cascade rhodium(III)-catalyzed ortho-C–H activation/annulation of thiobenzamides with aryl ethynyl ketones and subsequently copper(II)-promoted intramolecular C–H/C–H cross-coupling reactions. Mechanistic investigations suggest that Cu(II) plays two crucial roles by serving as a sulfide scavenger to regenerate the Rh(III) catalyst and promoting the intramolecular C–H/C–H cross-coupling reaction. This protocol greatly streamlines accesses to a variety of appealing tetracyclic benzo[a]fluorene skeletons, which may have potential biological activity and medicinal properties.
{"title":"One-Pot Synthesis of Dihydrobenzo[a]fluorenes via Cascade C–H Annulation of Thiobenzamide with Alkynes","authors":"Xingwen Pu, Zhangyi Fu, Yudong Yang, Di Wu, Pengchi Deng, Jingbo Lan","doi":"10.1021/acs.joc.4c01228","DOIUrl":"https://doi.org/10.1021/acs.joc.4c01228","url":null,"abstract":"We herein disclose a highly efficient one-pot synthetic strategy for dihydrobenzo[<i>a</i>]fluorenes via cascade rhodium(III)-catalyzed <i>ortho</i>-C–H activation/annulation of thiobenzamides with aryl ethynyl ketones and subsequently copper(II)-promoted intramolecular C–H/C–H cross-coupling reactions. Mechanistic investigations suggest that Cu(II) plays two crucial roles by serving as a sulfide scavenger to regenerate the Rh(III) catalyst and promoting the intramolecular C–H/C–H cross-coupling reaction. This protocol greatly streamlines accesses to a variety of appealing tetracyclic benzo[<i>a</i>]fluorene skeletons, which may have potential biological activity and medicinal properties.","PeriodicalId":57,"journal":{"name":"The Journal of Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":4.354,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1021/acs.jpcc.4c05078
Nobuyoshi Koga, Mito Hotta, Loic Favergeon
A kinetic theory and its application to the hydration reaction of inorganic salts were investigated with the aim of developing a universal description over a range of temperatures (T) and partial pressures of water vapor (p(H2O)). The hydration reaction of lithium sulfate anhydride (LS-AH) to form its monohydrate was selected as a model reaction and systematically traced at different T and p(H2O) values using a humidity-controlled thermogravimetry. The hydration process exhibited an induction period (IP) at a constant temperature. Subsequently, a sigmoidal mass gain process was observed, which was attributed to a consecutive surface reaction (SR) and phase boundary-controlled reaction (PBR). The reaction rates of the IP and mass gain process exhibited a reduction and an increase, respectively, with increasing T and p(H2O) values. A conventional kinetic analysis that did not consider the effect of p(H2O) revealed several issues with the universal kinetic description. These issues were addressed in steps with the development of an extended kinetic equation, which was formulated by incorporating an accommodation function into the fundamental kinetic equation. Consequently, the IP and mass gain processes of the LS-AH hydration were universally described over a range of T and p(H2O) values, and intrinsic kinetic parameters with reasonable physicochemical significance were determined. Furthermore, this approach was extended to the physico-geometrical kinetic modeling, based on the consecutive IP–SR–PBR model.
研究了一种动力学理论及其在无机盐水合反应中的应用，目的是对一系列温度（T）和水蒸气分压（p(H2O)）进行通用描述。研究人员选择了硫酸锂酸酐（LS-AH）形成其一水合物的水合反应作为模型反应，并使用湿度控制热重仪对不同温度和 p(H2O) 值下的反应进行了系统追踪。在恒温条件下，水合过程表现出一个诱导期（IP）。随后，观察到一个质量增加的正弦曲线过程，该过程归因于连续的表面反应（SR）和相界控制反应（PBR）。随着 T 值和 p(H2O) 值的增加，IP 和质量增加过程的反应速率分别出现了下降和上升。不考虑 p(H2O) 影响的传统动力学分析表明，通用动力学描述存在一些问题。为了解决这些问题，我们开发了一个扩展动力学方程，将调适函数纳入基本动力学方程。因此，LS-AH 水合的 IP 和质量增加过程在一定的 T 和 p(H2O) 值范围内得到了普遍描述，并确定了具有合理物理化学意义的内在动力学参数。此外，在连续 IP-SR-PBR 模型的基础上，该方法还扩展到了物理几何动力学建模。
{"title":"Hydration Kinetics in Inorganic Salt–Water Vapor Systems: A Case of Lithium Sulfate","authors":"Nobuyoshi Koga, Mito Hotta, Loic Favergeon","doi":"10.1021/acs.jpcc.4c05078","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c05078","url":null,"abstract":"A kinetic theory and its application to the hydration reaction of inorganic salts were investigated with the aim of developing a universal description over a range of temperatures (<i>T</i>) and partial pressures of water vapor (<i>p</i>(H<sub>2</sub>O)). The hydration reaction of lithium sulfate anhydride (LS-AH) to form its monohydrate was selected as a model reaction and systematically traced at different <i>T</i> and <i>p</i>(H<sub>2</sub>O) values using a humidity-controlled thermogravimetry. The hydration process exhibited an induction period (IP) at a constant temperature. Subsequently, a sigmoidal mass gain process was observed, which was attributed to a consecutive surface reaction (SR) and phase boundary-controlled reaction (PBR). The reaction rates of the IP and mass gain process exhibited a reduction and an increase, respectively, with increasing <i>T</i> and <i>p</i>(H<sub>2</sub>O) values. A conventional kinetic analysis that did not consider the effect of <i>p</i>(H<sub>2</sub>O) revealed several issues with the universal kinetic description. These issues were addressed in steps with the development of an extended kinetic equation, which was formulated by incorporating an accommodation function into the fundamental kinetic equation. Consequently, the IP and mass gain processes of the LS-AH hydration were universally described over a range of <i>T</i> and <i>p</i>(H<sub>2</sub>O) values, and intrinsic kinetic parameters with reasonable physicochemical significance were determined. Furthermore, this approach was extended to the physico-geometrical kinetic modeling, based on the consecutive IP–SR–PBR model.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":null,"pages":null},"PeriodicalIF":4.126,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruoqi Li, Rui Zhang, Ye Li, Chunguang Liu, Ping Wang, Hongwen Sun, Lei Wang
The foliar uptake of Fe3O4, Cr2O3, CuO, and ZnO nanoparticles (NPs) by maize (Zea mays L.) was studied in a lab-scale experiment. The significant increase of Fe concentrations in leaves exposed to Fe3O4 was observed in both stomatal closing and stomatal opening treatments, suggesting the presence of a nonstomatal uptake. In parallel treatments with equal doses of Fe3O4 (∼200 nm), Cr2O3 (∼300 nm), CuO (∼30 nm), and ZnO (∼40 nm) (20–200 μg), the retention percentage of Fe in the leaves (21.0–69.0%) was higher than that of Cr, Cu, and Zn (0.5–14.0%). The steric hindrance effect seems more important for NPs of >200 nm, while hydrophobic surface and negative charge promote the foliar uptake of NPs smaller than 200 nm. The accumulation of NPs in the cuticle was observed through dark-field hyperspectral microscopy. Cr2O3, Fe3O4, and CuO NPs were difficult to penetrate the cuticle. In comparison, ZnO further migrated and distributed within the extracellular space of epidermal and mesophyll cells of the exposed leaf, possibly due to its comparatively higher solubility and hydrophilicity. The findings highlight the potential of the nonstomatal uptake, which might be a critical route for metallic oxide NPs to enter the food chain.
{"title":"Foliar Uptake and Distribution of Metallic Oxide Nanoparticles in Maize (Zea mays L.) Leaf","authors":"Ruoqi Li, Rui Zhang, Ye Li, Chunguang Liu, Ping Wang, Hongwen Sun, Lei Wang","doi":"10.1021/acs.est.4c00991","DOIUrl":"https://doi.org/10.1021/acs.est.4c00991","url":null,"abstract":"The foliar uptake of Fe<sub>3</sub>O<sub>4</sub>, Cr<sub>2</sub>O<sub>3</sub>, CuO, and ZnO nanoparticles (NPs) by maize (<i>Zea mays</i> L.) was studied in a lab-scale experiment. The significant increase of Fe concentrations in leaves exposed to Fe<sub>3</sub>O<sub>4</sub> was observed in both stomatal closing and stomatal opening treatments, suggesting the presence of a nonstomatal uptake. In parallel treatments with equal doses of Fe<sub>3</sub>O<sub>4</sub> (∼200 nm), Cr<sub>2</sub>O<sub>3</sub> (∼300 nm), CuO (∼30 nm), and ZnO (∼40 nm) (20–200 μg), the retention percentage of Fe in the leaves (21.0–69.0%) was higher than that of Cr, Cu, and Zn (0.5–14.0%). The steric hindrance effect seems more important for NPs of >200 nm, while hydrophobic surface and negative charge promote the foliar uptake of NPs smaller than 200 nm. The accumulation of NPs in the cuticle was observed through dark-field hyperspectral microscopy. Cr<sub>2</sub>O<sub>3</sub>, Fe<sub>3</sub>O<sub>4</sub>, and CuO NPs were difficult to penetrate the cuticle. In comparison, ZnO further migrated and distributed within the extracellular space of epidermal and mesophyll cells of the exposed leaf, possibly due to its comparatively higher solubility and hydrophilicity. The findings highlight the potential of the nonstomatal uptake, which might be a critical route for metallic oxide NPs to enter the food chain.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":null,"pages":null},"PeriodicalIF":9.028,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1021/acs.jpcc.4c03634
Zeming He, Wenxi Xie, Siyang Zhang, Yin Gao, Ashraf Y. Elnaggar, Juanna Ren, Islam H. El Azab, Zeinhom M. El-Bahy, Ming Yang, Hang Zhang, Zhanhu Guo
Glass exhibits high transmittance in the solar radiation band but high absorbance in the mid-far infrared (MIR) band, which causes a poor energy-saving effect. Thermal insulation coatings offer the most effective solution to address this. Among these, nano-cesium tungsten bronze (CsxWO3) had a strong blocking effect in the solar radiation band due to its intrinsic absorption, local surface plasmon resonance, and small polaron absorption, but its reflectivity in the MIR band was very low. Conversely, silver nanowires (AgNWs) formed a dense network structure with low transmittance and high reflectance in the MIR band; however, when mixed into Cs0.32WO3 slurries, the solar radiation-blocking ability was weakened. In order to assess the impact of AgNWs on the properties of Cs0.32WO3 films, this study collected experimental data from different Cs0.32WO3 films doped with AgNWs for multilayer perceptron (MLP) neural network machine learning. The trained models exhibited efficient and accurate prediction abilities. A large number of extrapolated independent variables were input to the trained MLP models using the grid search method, and then the predicted results of dependent variables were displayed in three-dimensional (3D) models to more intuitively show the influence of doping AgNWs on the optical performance of different Cs0.32WO3 films. Through an optimization analysis of two 3D models of T550 nm (transmittance at 550 nm) and SC (shading coefficient), two transition values of T550 nm were found: 69.5 and 64.2%. When T550 nm surpassed 69.5%, the SC value of nondoped Cs0.32WO3 films was the lowest. Conversely, when T550nm was below 69.5%, doping with AgNWs decreased the SC value of Cs0.32WO3 films. Using the optimal mixture of Cs0.32WO3 slurries and AgNW slurry at a ratio of 1:3, the SC value of nondoped Cs0.32WO3 films was lower when T550nm exceeded 64.2%. Conversely, when T550 nmwas below 64.2%, the same mixture resulted in a lower SC value. These predicted results and their accuracy were verified by experiments and provided important technical guidance and method support for future research and the application of high-performance Cs0.32WO3 films.
{"title":"Optimizing Spectral Properties of Cesium Tungsten Bronze Films Doped with Silver Nanowires Based on the Machine Learning Method","authors":"Zeming He, Wenxi Xie, Siyang Zhang, Yin Gao, Ashraf Y. Elnaggar, Juanna Ren, Islam H. El Azab, Zeinhom M. El-Bahy, Ming Yang, Hang Zhang, Zhanhu Guo","doi":"10.1021/acs.jpcc.4c03634","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c03634","url":null,"abstract":"Glass exhibits high transmittance in the solar radiation band but high absorbance in the mid-far infrared (MIR) band, which causes a poor energy-saving effect. Thermal insulation coatings offer the most effective solution to address this. Among these, nano-cesium tungsten bronze (Cs<i><sub>x</sub></i>WO<sub>3</sub>) had a strong blocking effect in the solar radiation band due to its intrinsic absorption, local surface plasmon resonance, and small polaron absorption, but its reflectivity in the MIR band was very low. Conversely, silver nanowires (AgNWs) formed a dense network structure with low transmittance and high reflectance in the MIR band; however, when mixed into Cs<sub>0.32</sub>WO<sub>3</sub> slurries, the solar radiation-blocking ability was weakened. In order to assess the impact of AgNWs on the properties of Cs<sub>0.32</sub>WO<sub>3</sub> films, this study collected experimental data from different Cs<sub>0.32</sub>WO<sub>3</sub> films doped with AgNWs for multilayer perceptron (MLP) neural network machine learning. The trained models exhibited efficient and accurate prediction abilities. A large number of extrapolated independent variables were input to the trained MLP models using the grid search method, and then the predicted results of dependent variables were displayed in three-dimensional (3D) models to more intuitively show the influence of doping AgNWs on the optical performance of different Cs<sub>0.32</sub>WO<sub>3</sub> films. Through an optimization analysis of two 3D models of <i>T</i><sub>550 nm</sub> (transmittance at 550 nm) and SC (shading coefficient), two transition values of <i>T</i><sub>550 nm</sub> were found: 69.5 and 64.2%. When <i>T</i><sub>550 nm</sub> surpassed 69.5%, the SC value of nondoped Cs<sub>0.32</sub>WO<sub>3</sub> films was the lowest. Conversely, when <i>T</i><sub>550</sub> <sub>nm</sub> was below 69.5%, doping with AgNWs decreased the SC value of Cs<sub>0.32</sub>WO<sub>3</sub> films. Using the optimal mixture of Cs<sub>0.32</sub>WO<sub>3</sub> slurries and AgNW slurry at a ratio of 1:3, the SC value of nondoped Cs<sub>0.32</sub>WO<sub>3</sub> films was lower when <i>T</i><sub>550</sub> <sub>nm</sub> exceeded 64.2%. Conversely, when <i>T</i><sub>550 nm</sub>was below 64.2%, the same mixture resulted in a lower SC value. These predicted results and their accuracy were verified by experiments and provided important technical guidance and method support for future research and the application of high-performance Cs<sub>0.32</sub>WO<sub>3</sub> films.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":null,"pages":null},"PeriodicalIF":4.126,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1021/acs.jpcc.4c05186
Yangmin Kuang, Wuqin Li, Zitian Lin, Yanpeng Zheng, Vincent S. J. Craig
Worldwide natural gas hydrates are considered the largest hydrocarbon source. A challenge in accessing these resources is the memory effect exhibited by gas hydrates, in that gas hydrate nucleation is more rapid in solutions in which gas hydrate has previously decomposed. A number of hypotheses exist to explain this memory effect, including the proposal that nanobubbles play a role. Bulk nanobubbles show surprising stability and have been implicated in gas hydrate nucleation and growth. Here the influence of both surface and bulk nanobubbles on the hydrate memory effect are explored. The presence of both surface and bulk nanobubbles were confirmed in hydrate decomposition solutions by different methods. The influence of nanobubbles on the memory effect was demonstrated through the influence of degassing on the induction time and nucleation probability estimation. Also, the hydrate nucleation and growth characteristics on the surface of bulk micronanobubbles in pure water, electrolyte, and surfactant solutions was studied. It was shown that gas hydrate crystals coated bubbles in pure water, but the formation of this coating was inhibited in surfactant solutions. Electrolyte also inhibited the coating of bubbles with hydrate crystals. This work demonstrates that nanobubbles strongly influence the memory effect in gas hydrates, by both directly influencing gas hydrate nucleation and through wall effects via surface nanobubbles. This work does not preclude other mechanisms proposed for the memory effect in gas hydrate formation.
{"title":"Experimental Study on Memory Effect of Gas Hydrates: Interaction between Micronanobubbles and Solute Molecules","authors":"Yangmin Kuang, Wuqin Li, Zitian Lin, Yanpeng Zheng, Vincent S. J. Craig","doi":"10.1021/acs.jpcc.4c05186","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c05186","url":null,"abstract":"Worldwide natural gas hydrates are considered the largest hydrocarbon source. A challenge in accessing these resources is the memory effect exhibited by gas hydrates, in that gas hydrate nucleation is more rapid in solutions in which gas hydrate has previously decomposed. A number of hypotheses exist to explain this memory effect, including the proposal that nanobubbles play a role. Bulk nanobubbles show surprising stability and have been implicated in gas hydrate nucleation and growth. Here the influence of both surface and bulk nanobubbles on the hydrate memory effect are explored. The presence of both surface and bulk nanobubbles were confirmed in hydrate decomposition solutions by different methods. The influence of nanobubbles on the memory effect was demonstrated through the influence of degassing on the induction time and nucleation probability estimation. Also, the hydrate nucleation and growth characteristics on the surface of bulk micronanobubbles in pure water, electrolyte, and surfactant solutions was studied. It was shown that gas hydrate crystals coated bubbles in pure water, but the formation of this coating was inhibited in surfactant solutions. Electrolyte also inhibited the coating of bubbles with hydrate crystals. This work demonstrates that nanobubbles strongly influence the memory effect in gas hydrates, by both directly influencing gas hydrate nucleation and through wall effects via surface nanobubbles. This work does not preclude other mechanisms proposed for the memory effect in gas hydrate formation.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":null,"pages":null},"PeriodicalIF":4.126,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fan Zhang, Yawen Tian, Yitao Pan, Nan Sheng, Jiayin Dai
Binding with proteins is a critical molecular initiating event through which environmental pollutants exert toxic effects in humans. Previous studies have been limited by the availability of three-dimensional (3D) protein structures and have focused on only a small set of environmental contaminants. Using the highly accurate 3D protein structure predicted by AlphaFold2, this study explored over 60 million interactions obtained through molecular docking between 20,503 human proteins and 1251 potential endocrine-disrupting chemicals. A total of 66,613,773 docking results were obtained, 1.2% of which were considered to be high binding, as their docking scores were lower than −7. Monocyte to macrophage differentiation factor 2 (MMD2) was predicted to interact with the highest number of environmental pollutants (526), with polychlorinated biphenyls and polychlorinated dibenzofurans accounting for a significant proportion. Dimension reduction and clustering analysis revealed distinct protein profiles characterized by high binding affinities for perfluoroalkyl and polyfluoroalkyl substances (PFAS), phthalate-like chemicals, and other pollutants, consistent with their uniquely enriched pathways. Further structural analysis indicated that binding pockets with a high proportion of charged amino acid residues, relatively low α-helix content, and high β-sheet content were more likely to bind to PFAS than others. This study provides insights into the toxicity pathways of various pollutants impacting human health and offers novel perspectives for the establishment and expansion of adverse outcome pathway-based models.
{"title":"Interactions of Potential Endocrine-Disrupting Chemicals with Whole Human Proteome Predicted by AlphaFold2 Using an In Silico Approach","authors":"Fan Zhang, Yawen Tian, Yitao Pan, Nan Sheng, Jiayin Dai","doi":"10.1021/acs.est.4c03774","DOIUrl":"https://doi.org/10.1021/acs.est.4c03774","url":null,"abstract":"Binding with proteins is a critical molecular initiating event through which environmental pollutants exert toxic effects in humans. Previous studies have been limited by the availability of three-dimensional (3D) protein structures and have focused on only a small set of environmental contaminants. Using the highly accurate 3D protein structure predicted by AlphaFold2, this study explored over 60 million interactions obtained through molecular docking between 20,503 human proteins and 1251 potential endocrine-disrupting chemicals. A total of 66,613,773 docking results were obtained, 1.2% of which were considered to be high binding, as their docking scores were lower than −7. Monocyte to macrophage differentiation factor 2 (MMD2) was predicted to interact with the highest number of environmental pollutants (526), with polychlorinated biphenyls and polychlorinated dibenzofurans accounting for a significant proportion. Dimension reduction and clustering analysis revealed distinct protein profiles characterized by high binding affinities for perfluoroalkyl and polyfluoroalkyl substances (PFAS), phthalate-like chemicals, and other pollutants, consistent with their uniquely enriched pathways. Further structural analysis indicated that binding pockets with a high proportion of charged amino acid residues, relatively low α-helix content, and high β-sheet content were more likely to bind to PFAS than others. This study provides insights into the toxicity pathways of various pollutants impacting human health and offers novel perspectives for the establishment and expansion of adverse outcome pathway-based models.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":null,"pages":null},"PeriodicalIF":9.028,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1021/acs.jpclett.4c02062
Setare Mostajabi Sarhangi, Dmitry V. Matyushov
Friction to translational diffusion of ionic particles in polar liquids should scale linearly with the squared ion charge, according to standard theories. Substantial slowing of translational diffusion is expected for proteins in water. In contrast, our simulations of charge mutants of green fluorescent proteins in water show remarkable insensitivity of the translational diffusion constant to protein’s charge in the range of charges between −29 and +35. The friction coefficient is given as a product of the force variance and the memory function relaxation time. We find remarkably accurate equality between the variance of the electrostatic force and the negative cross-correlation of the electrostatic and van der Waals forces. The charge invariance of the diffusion constant is a combined effect of the force variance and relaxation time invariances with the protein charge. The temperature dependence of the protein diffusion constant is highly non-Arrhenius, with a fragile-to-strong crossover at the glass transition.
{"title":"Remarkable Insensitivity of Protein Diffusion to Protein Charge","authors":"Setare Mostajabi Sarhangi, Dmitry V. Matyushov","doi":"10.1021/acs.jpclett.4c02062","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c02062","url":null,"abstract":"Friction to translational diffusion of ionic particles in polar liquids should scale linearly with the squared ion charge, according to standard theories. Substantial slowing of translational diffusion is expected for proteins in water. In contrast, our simulations of charge mutants of green fluorescent proteins in water show remarkable insensitivity of the translational diffusion constant to protein’s charge in the range of charges between −29 and +35. The friction coefficient is given as a product of the force variance and the memory function relaxation time. We find remarkably accurate equality between the variance of the electrostatic force and the negative cross-correlation of the electrostatic and van der Waals forces. The charge invariance of the diffusion constant is a combined effect of the force variance and relaxation time invariances with the protein charge. The temperature dependence of the protein diffusion constant is highly non-Arrhenius, with a fragile-to-strong crossover at the glass transition.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":null,"pages":null},"PeriodicalIF":6.475,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Allylboration reactions of ketones catalyzed by BINOL derivatives can exhibit highly variable stereochemical courses depending on the nature and reactivity of the ketone substrate. In this Article, we put into perspective the relationship between the nature of the starting material and the active species involved in the asymmetric allyboration catalyzed by BINOL derivatives. This work, aimed at comparing different plausible mechanisms by density functional theory (DFT) at the M06-2X/6-311+G(d,p) level involving different types of allylboronates in the presence of the organocatalyst, leads to the confirmation of the hitherto accepted hypothesis of a reaction promoted by the transient cyclic allyl-1,3,2-dioxaborolane derived from BINOLs in the case of unactivated or weakly activated ketones such as indanone. A hypothetical scenario involving dimeric boronate species as chiral catalysts was also investigated.
{"title":"Allylboration of Ketones Catalyzed by BINOL Derivatives: Which Species Are Involved Depending on Substrate Reactivity?","authors":"Arnaud Martel, Rania Zaier, Julien Braire, Aurélie Macé, Joelle Vidal, Claudia Lalli, François Carreaux","doi":"10.1021/acs.joc.4c01343","DOIUrl":"https://doi.org/10.1021/acs.joc.4c01343","url":null,"abstract":"Allylboration reactions of ketones catalyzed by BINOL derivatives can exhibit highly variable stereochemical courses depending on the nature and reactivity of the ketone substrate. In this Article, we put into perspective the relationship between the nature of the starting material and the active species involved in the asymmetric allyboration catalyzed by BINOL derivatives. This work, aimed at comparing different plausible mechanisms by density functional theory (DFT) at the M06-2X/6-311+G(d,p) level involving different types of allylboronates in the presence of the organocatalyst, leads to the confirmation of the hitherto accepted hypothesis of a reaction promoted by the transient cyclic allyl-1,3,2-dioxaborolane derived from BINOLs in the case of unactivated or weakly activated ketones such as indanone. A hypothetical scenario involving dimeric boronate species as chiral catalysts was also investigated.","PeriodicalId":57,"journal":{"name":"The Journal of Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":4.354,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N2O and CO coexist in various industrial and mobile sources. The synergistic reaction of N2O and CO to generate N2 and CO2 has garnered significant research interest, but it remains extremely challenging. Herein, we constructed an atomically dispersed Rh-supported CeO2 catalyst with asymmetric Rh–O–Ce sites through gradient Rh 4d–O 2p–Ce 4f orbital coupling. This design effectively regulates the 4f electron states of Ce and promotes the electron filling of the O 3π* antibonding orbital to facilitate N–O bond cleavage. Near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) reveals that CO reacts with the surface-adsorbed O* generated by N2O decomposition through self-tandem catalysis, accelerating the rate-limiting step in N2O decomposition and activating the synergistic reaction of N2O and CO at temperatures as low as 115 °C. This work can guide the development of high-performance catalysts using the strategy of high-order orbital hybridization combined with the tandem concept to achieve versatile catalytic applications.
一氧化二氮和一氧化碳共存于各种工业和移动污染源中。N2O 和 CO 协同反应生成 N2 和 CO2 已引起研究人员的极大兴趣，但这一研究仍极具挑战性。在此，我们通过梯度 Rh 4d-O 2p-Ce 4f 轨道耦合，构建了具有不对称 Rh-O-Ce 位点的原子分散 Rh-supported CeO2 催化剂。这种设计有效地调节了 Ce 的 4f 电子状态，促进了 O 3π* 反键轨道的电子填充，从而促进了 N-O 键的裂解。近常压 X 射线光电子能谱（NAP-XPS）显示，CO 通过自串联催化作用与 N2O 分解产生的表面吸附 O* 发生反应，加快了 N2O 分解的限速步骤，并在低至 115 ℃ 的温度下激活了 N2O 和 CO 的协同反应。这项工作可指导利用高阶轨道杂化策略结合串联概念开发高性能催化剂，以实现催化应用的多样性。
{"title":"4d–2p–4f Gradient Orbital Coupling Enables Tandem Catalysis for Simultaneous Abatement of N2O and CO on Atomically Dispersed Rh/CeO2 Catalyst","authors":"Hao Liu, Shan Yang, Jinxing Mi, Chuanzhi Sun, Jianjun Chen, Junhua Li","doi":"10.1021/acs.est.4c02277","DOIUrl":"https://doi.org/10.1021/acs.est.4c02277","url":null,"abstract":"N<sub>2</sub>O and CO coexist in various industrial and mobile sources. The synergistic reaction of N<sub>2</sub>O and CO to generate N<sub>2</sub> and CO<sub>2</sub> has garnered significant research interest, but it remains extremely challenging. Herein, we constructed an atomically dispersed Rh-supported CeO<sub>2</sub> catalyst with asymmetric Rh–O–Ce sites through gradient Rh 4d–O 2p–Ce 4f orbital coupling. This design effectively regulates the 4f electron states of Ce and promotes the electron filling of the O 3π* antibonding orbital to facilitate N–O bond cleavage. Near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) reveals that CO reacts with the surface-adsorbed O* generated by N<sub>2</sub>O decomposition through self-tandem catalysis, accelerating the rate-limiting step in N<sub>2</sub>O decomposition and activating the synergistic reaction of N<sub>2</sub>O and CO at temperatures as low as 115 °C. This work can guide the development of high-performance catalysts using the strategy of high-order orbital hybridization combined with the tandem concept to achieve versatile catalytic applications.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":null,"pages":null},"PeriodicalIF":9.028,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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