It is still a great challenge to effectively optimize the electronic structure of photocatalysts for the sustainable and efficient conversion of solar energy to H2 energy.To resolve this issue,we report on the optimiz...It is still a great challenge to effectively optimize the electronic structure of photocatalysts for the sustainable and efficient conversion of solar energy to H2 energy.To resolve this issue,we report on the optimization of the electronic structure of hollow-concave carbon nitride(C3N4)by deviating the sp2-hybridized structure of its tri-s-triazine component from the two-dimensional plane.The embedded CuInS2 into C3N4(CuInS2@C3N4)demonstrates an increased light-capturing capability and the promoted directional transfer of the charge carrier.Research results reveal that the hollow structure with an apparent potential difference between the concave and convex C3N4 drives the directional transfer of the photoinduced electrons from the Cu 2p orbital of CuInS2 to the N 1s orbital of C3N4 with the S-scheme principle.The H2 evolution efficiency over CuInS2@C3N4 is up to 373μmol?h^-1 g^-1 under visible irradiation,which is 1.57 and 1.35 times higher than those over the bulk g-C3N4 with 1 wt%Pt(238μmol?h^-1 g^-1)and g-C3N4 with 3 wt%Pd(276μmol?h^-1 g^-1),respectively.This suggests that the apparent potential difference of the hollow C3N4 results in an efficient reaction between the photogenerated electrons and H2O.This work supplies a new strategy for enhancing the sustainable solar conversion performance of carbon nitride,which can also be suitable for other semiconductors.展开更多
Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has m...Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential(AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources(Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen(TN) and total phosphorus(TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.展开更多
Bacterial small laccases(SLAC) are promising industrial biocatalysts due to their ability to oxidize a broad range of substrates with exceptional thermostability and tolerance for alkaline p H. Electron transfer betwe...Bacterial small laccases(SLAC) are promising industrial biocatalysts due to their ability to oxidize a broad range of substrates with exceptional thermostability and tolerance for alkaline p H. Electron transfer between substrate, copper centers, and O2is one of the key steps in the catalytic turnover of SLAC. However, limited research has been conducted on the electron transfer pathway of SLAC and SLAC-catalyzed reactions, hindering further engineering of SLAC to produce tunable biocatalysts for novel applications. Herein, the combinational use of electron paramagnetic resonance(EPR) and ultraviolet-visible(UV-vis) spectroscopic methods coupled with redox titration were employed to monitor the electron transfer processes and obtain further insights into the electron transfer pathway in SLAC. The reduction potentials for type 1 copper(T1Cu), type 2 copper(T2Cu) and type 3copper(T3Cu) were determined to be 367 ± 2 mV, 378 ± 5 m V and 403 ± 2 mV,respectively. Moreover, the reduction potential of a selected substrate of SLAC, hydroquinone(HQ), was determined to be 288 mV using cyclic voltammetry(CV). In this way, an electron transfer pathway was identified based on the reduction potentials. Specifically,electrons are transferred from HQ to T1Cu, then to T2Cu and T3Cu, and finally to O2.Furthermore, superhyperfine splitting observed via EPR during redox titration indicated a modification in the covalency of T2Cu upon electron uptake, suggesting a conformational alteration in the protein environment surrounding the copper sites, which could potentially influence the reduction potential of the copper sites during catalytic processes. The results presented here not only provide a comprehensive method for analyzing the electron transfer pathway in metalloenzymes through reduction potential measurements, but also offer valuable insights for further engineering and directed evolution studies of SLAC in the aim for biotechnological and industrial applications.展开更多
为缓解跨域推荐中目标域数据稀疏和冷启动问题,综合增强嵌入、嵌入迁移、注意力机制调整和跨域推荐技术,提出一种融合深度特征提取和注意力机制的跨域推荐模型(cross-domain recommendation model of deep feature extraction and atten...为缓解跨域推荐中目标域数据稀疏和冷启动问题,综合增强嵌入、嵌入迁移、注意力机制调整和跨域推荐技术,提出一种融合深度特征提取和注意力机制的跨域推荐模型(cross-domain recommendation model of deep feature extraction and attention mechanism,CRDFEAM).利用潜在因子模型将类型相似度合并到矩阵分解过程,挖掘项目类型的隐性偏好.相比评分这一显性偏好,项目类型能更充分获取用户特征.在跨域迁移时,用分布对齐方式使域间差异最小化,以减少两个领域特征之间的数据分布差异.相对于直接迁移,分布对齐方式具有更强的可解释性.在特征调整过程中,引入多层感知机(multilayer perceptron,MLP)映射,并使用注意力机制进一步调整用户特征,使源域中没有出现过的目标域用户注意到源域用户的特征信息,同时也使源域中出现过的目标域用户注意到目标域中的项目特征信息.在真实数据集Movielens(M)、Netflix(N)和Douban(D)上的实验验证结果表明,引入MLP映射嵌入的CRDFEAM+模型的均方根误差(root mean square error,RMSE)值较基准模型跨域潜在特征映射(cross-domain latent feature mapping,CDLFM)平均提升9.88%,平均绝对误差(mean absolute error,MAE)值平均提升11.14%.研究验证了CRDFEAM+模型的跨域推荐效果,能够更充分地提取用户特征,有效缓解目标域信息不足问题.展开更多
基金Study was supported by the National Natural Science Foundation of China(21871155)the K.C.Wong Magna Fund in Ningbo University,Fan 3315 PlanYongjiang Scholar Plan~~
文摘It is still a great challenge to effectively optimize the electronic structure of photocatalysts for the sustainable and efficient conversion of solar energy to H2 energy.To resolve this issue,we report on the optimization of the electronic structure of hollow-concave carbon nitride(C3N4)by deviating the sp2-hybridized structure of its tri-s-triazine component from the two-dimensional plane.The embedded CuInS2 into C3N4(CuInS2@C3N4)demonstrates an increased light-capturing capability and the promoted directional transfer of the charge carrier.Research results reveal that the hollow structure with an apparent potential difference between the concave and convex C3N4 drives the directional transfer of the photoinduced electrons from the Cu 2p orbital of CuInS2 to the N 1s orbital of C3N4 with the S-scheme principle.The H2 evolution efficiency over CuInS2@C3N4 is up to 373μmol?h^-1 g^-1 under visible irradiation,which is 1.57 and 1.35 times higher than those over the bulk g-C3N4 with 1 wt%Pt(238μmol?h^-1 g^-1)and g-C3N4 with 3 wt%Pd(276μmol?h^-1 g^-1),respectively.This suggests that the apparent potential difference of the hollow C3N4 results in an efficient reaction between the photogenerated electrons and H2O.This work supplies a new strategy for enhancing the sustainable solar conversion performance of carbon nitride,which can also be suitable for other semiconductors.
基金supported by the National Natural Science Foundation of China(No.51808531)the Major Science and Technology Program for Water Pollution Control and Treatment(No.2018YFE0204101)。
文摘Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential(AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources(Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen(TN) and total phosphorus(TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.
基金supported by the National Natural Science Foundation of China (21825703, 21927814)the National Key R&D Program of China (2019YFA0405600, 2019YFA0706900, 2021YFA1200104, 2022YFC3400500)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB0540200, XDB37040201)Plans for Major Provincial Science&Technology Projects (202303a07020004)Basic Research Program Based on Major Scientific Infrastructures,CAS (JZHKYPT-2021-05)the Youth Innovation Promotion Association,CAS (2022455)
文摘Bacterial small laccases(SLAC) are promising industrial biocatalysts due to their ability to oxidize a broad range of substrates with exceptional thermostability and tolerance for alkaline p H. Electron transfer between substrate, copper centers, and O2is one of the key steps in the catalytic turnover of SLAC. However, limited research has been conducted on the electron transfer pathway of SLAC and SLAC-catalyzed reactions, hindering further engineering of SLAC to produce tunable biocatalysts for novel applications. Herein, the combinational use of electron paramagnetic resonance(EPR) and ultraviolet-visible(UV-vis) spectroscopic methods coupled with redox titration were employed to monitor the electron transfer processes and obtain further insights into the electron transfer pathway in SLAC. The reduction potentials for type 1 copper(T1Cu), type 2 copper(T2Cu) and type 3copper(T3Cu) were determined to be 367 ± 2 mV, 378 ± 5 m V and 403 ± 2 mV,respectively. Moreover, the reduction potential of a selected substrate of SLAC, hydroquinone(HQ), was determined to be 288 mV using cyclic voltammetry(CV). In this way, an electron transfer pathway was identified based on the reduction potentials. Specifically,electrons are transferred from HQ to T1Cu, then to T2Cu and T3Cu, and finally to O2.Furthermore, superhyperfine splitting observed via EPR during redox titration indicated a modification in the covalency of T2Cu upon electron uptake, suggesting a conformational alteration in the protein environment surrounding the copper sites, which could potentially influence the reduction potential of the copper sites during catalytic processes. The results presented here not only provide a comprehensive method for analyzing the electron transfer pathway in metalloenzymes through reduction potential measurements, but also offer valuable insights for further engineering and directed evolution studies of SLAC in the aim for biotechnological and industrial applications.
文摘为缓解跨域推荐中目标域数据稀疏和冷启动问题,综合增强嵌入、嵌入迁移、注意力机制调整和跨域推荐技术,提出一种融合深度特征提取和注意力机制的跨域推荐模型(cross-domain recommendation model of deep feature extraction and attention mechanism,CRDFEAM).利用潜在因子模型将类型相似度合并到矩阵分解过程,挖掘项目类型的隐性偏好.相比评分这一显性偏好,项目类型能更充分获取用户特征.在跨域迁移时,用分布对齐方式使域间差异最小化,以减少两个领域特征之间的数据分布差异.相对于直接迁移,分布对齐方式具有更强的可解释性.在特征调整过程中,引入多层感知机(multilayer perceptron,MLP)映射,并使用注意力机制进一步调整用户特征,使源域中没有出现过的目标域用户注意到源域用户的特征信息,同时也使源域中出现过的目标域用户注意到目标域中的项目特征信息.在真实数据集Movielens(M)、Netflix(N)和Douban(D)上的实验验证结果表明,引入MLP映射嵌入的CRDFEAM+模型的均方根误差(root mean square error,RMSE)值较基准模型跨域潜在特征映射(cross-domain latent feature mapping,CDLFM)平均提升9.88%,平均绝对误差(mean absolute error,MAE)值平均提升11.14%.研究验证了CRDFEAM+模型的跨域推荐效果,能够更充分地提取用户特征,有效缓解目标域信息不足问题.
