追踪SrTiO3/CoP/Mo2C纳米纤维中的电荷转移路径以增强光催化产生太阳燃料

光催化产生太阳燃料因其低成本和零碳排放而成为解决能源危机的研究热点,但光激发载流子对的快速体相复合是需要解决的根本问题.本文在钛酸锶(SrTiO₃)纳米纤维上嵌入磷化钴(CoP)和碳化钼(Mo₂C)构筑了双助催化剂体系.与纯SrTiO₃纳米纤维和二元样品相比,双助催化剂体系显著提高了析氢和二氧化碳还原性能.双助催化剂体系有利于有效促进空间电荷分离并提高光催化性能.此外,SrTiO₃与助催化剂之间形成肖特基结,使光激发电子从SrTiO₃快速转移到助催化剂,实现了光激发电子的有效分离并延长了光激发电子寿命.通过原位辐照X射线光电子能谱测试(ISI-XPS)确定了SrTiO₃和助催化剂之间的电子转移路线,根据紫外-可见漫反射光谱(UV-VisDRS)和紫外光电子能谱(UPS)提出了SrTiO₃和助催化剂的能带结构.结果表明,双助催化剂促进了电荷分离并增强了光催化性能.扫描电镜、透射电镜、高分辨透射电镜及其对应的元素分布结果表明,成功构筑了双助催化剂体系,且助催化剂的引入未影响SrTiO₃纳米纤维的结构.SrTiO₃纯样品表现出较低的光催化产氢活性,引入CoP后产氢性能得到提升并在CoP负载量为6%时达到最高.电化学测试、光致发光测试和瞬态光电压测试表明,引入CoP后的复合样品电化学性能得到提升,表现出更及时的电荷分离、更低的起始电位、更低的载流子复合率以及更长的载流子寿命.进一步在SrTiO₃纳米纤维上嵌入CoP和Mo₂C,构筑双助催化剂体系,其光催化产氢活性显著提升.同时,得益于SrTiO₃独特的能带位置,该双催化剂体系也表现出良好的二氧化碳还原性能.采用ISI-XPS,UPS,UV-VisDRS等研究了双助催化剂的催化机理以及电子转移路径.UPS和UV-VisDRS结果表明,SrTiO₃具有较高的功函数,CoP的功函数较低,Mo₂C的功函数位于SrTiO₃和CoP之间,因此电子倾向于从SrTiO₃的导带流向Mo₂C再流向CoP,同时形成肖特基势垒使得电子难以流回SrTiO₃,从而实现载流子的及时分离以及延长电子寿命.此外,ISI-XPS的结合能大小变化表明,电子是从SrTiO₃流到Mo₂C再流向CoP.综上,本文制备了双助催化剂修饰的SrTiO₃纳米纤维,证明了CoP和Mo₂C在改性宽带隙半导体中的作用,并证实了SrTiO₃和助催化剂之间光激发载流子的有效空间分离,探索了光激发电子在双助催化剂体系间的流向,为后续研究提供了理论依据和探索思路.     

Dual Toeplitz operators on orthogonal complement of the harmonic Dirichlet space

In this paper, we study some algebraic and spectral properties of dual Toeplitz operators on the orthogonal complement of the harmonic Dirichlet space of the unit disk.     

Dual mixed Orlicz–Brunn–Minkowski inequality and dual Orlicz mixed quermassintegrals

The dual Orlicz–Brunn–Minkowski inequality is extended from volume to dual quermassintegrals. As application, a dual mixed log-Brunn–Minkowski inequality is obtained. Moreover, dual Orlicz mixed quermassintegrals are defined and a dual Orlicz–Minkowski inequality and a dual mixed log-Minkowski inequality are established.     

Complementary energy release rates and dual conservation integrals in micropolar elasticity

The complementary energy momentum tensor, expressed in terms of the spatial gradients of stress and couple-stress, is used to construct the and conservation integrals of infinitesimal micropolar elasticity. The derived integrals are related to the release rates of the complementary potential energy associated with a defect translation or rotation. A nonconserved integral is also derived and related to the energy release rate that is associated with a self-similar cavity expansion. The results are compared to those obtained on the basis of the classical energy momentum tensor, expressed in terms of the spatial gradients of displacement and rotation, and the release rates of the potential energy. It is shown that the evaluation of the complementary conservation integrals is of similar complexity to that of the classical conservation integrals, so that either can be effectively used in the energetic analysis of the mechanics of defects. The two-dimensional versions of the dual conservation integrals are then derived and applied to an out-of-plane shearing of a long cracked slab.     

On the interaction between two fixed spherical particles

The variation of the drag (C_D) and lift coefficients (C_L) of two fixed solid spherical particles placed at different positions relative each other is studied. Simulations are carried out for particle Reynolds numbers of 50, 100 and 200 and the particle position is defined by the angle between the line connecting the centers of the particles and the free-stream direction (α) and the separation distance (d₀) between the particles. The flow around the particles is simulated using two different methods; the Lattice Boltzmann Method (LBM), using two different computational codes, and a conventional finite difference approach, where the Volume of Solid Method (VOS) is used to represent the particles. Comparisons with available numerical and experimental data show that both methods can be used to accurately resolve the flow field around particles and calculate the forces the particles are subjected to. Independent of the Reynolds number, the largest change in drag, as compared to the single particle case, occurs for particles placed in tandem formation. Compared to a single particle, the drag reduction for the secondary particle in tandem arrangement is as high as 60%, 70% and 80% for Re = 50, 100 and 200, respectively. The development of the recirculation zone is found to have a significant influence on the drag force. Depending on the flow situation in-between the particles for various particle arrangements, attraction and repulsion forces are detected due to low and high pressure regions, respectively. The results show that the inter-particle forces are not negligible even under very dilute conditions.     

Dual inhibitors of Interleukin-6 and acetylcholinesterase for treatment of Alzheimer's disease: Design,docking, synthesis and biological evaluation

Multitarget compounds intercept two or more functionally complementary pathways simultaneously, and are therefore considered to have potential in effectively treating complex multifactorial diseases like Alzheimer's disease (AD). In the present study, novel molecules are designed by coupling a chromone and a N,N-disubstituted carbamoyl amine as pharmacophore for interleukin-6 (IL-6) and acetylcholinesterase (AChE) inhibition, respectively. Four series (Y1–Y4) of 40 compounds are designed by using alkyl linkers of different lengths (1–4 carbon atoms) for the coupling of the two selected pharmacophore. Docking of all designed compounds in AChE leads to the identification of twelve best fit compounds (Docking score >8.3). The data suggests that a 1- or 2-carbon atom linker is the most conducive to orient the pharmacophore for optimum binding with AChE active site. The predicted ADME properties of the 12 selected compounds suggest that these can cross the blood brain barrier (BBB) with good oral bioavailability. These compounds are synthesised and evaluated for anti-AChE activity. Five compounds, showing >45% inhibition of AChE, are further evaluated for IL-6 inhibitory activity. Compound Y1f is found to be the most potent inhibitor of both AChE and IL-6 (IC₅₀ 0.7 and 0.8 ​μM, respectively). It suggests that a chromone moiety connected to a piperidine ring through a 1-carbon atom linker may provide a useful template to medical chemists for the development of new chemical entities effective against AD.     

Tuning the nucleophilic attack and the reductive action of glycine on graphene oxide under basic medium

Amino acids are important compounds for GO functionalization because they can improve GO properties for many applications ranging from biomedicine to depollution. However, amino acids can act as nucleophiles or as reducing agents for GO functionalization or reduction, respectively. Hence, we systematically studied the GO functionalization/reduction using glycine as a model amino acid under basic conditions at room temperature. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the modified GO with glycine. We found that low glycine concentrations produced an epoxide ring opening reaction, whereas an increase in glycine concentration led to GO reduction. The basic medium allowed to conserve the carboxylic acid groups, whereas the GO reduction mechanism was governed by the partial hydrolysis of epoxide groups and the subsequent reduction of carboxylic acids to carbonyls. This article opens up the opportunity to study and control the conditions in which different amino acids could be used for either GO functionalization or GO reduction.     

中心金属或配体刚性调控的α-酮酸酯对硝基烯的不对称共轭加成

通过手性二胺配体与Cu或Ni络合合成了手性金属催化剂,并将其应用于α-酮酸酯对硝基烯的不对称共轭加成反应中,发展了通过改变中心金属或调节配体刚性实现反应对映选择性反转的策略.使用同一手性二胺配体(1S,1'S)-1,1'-联异吲哚啉,与不同的金属前体(Cu(OAc)2·H2O与Ni(OAc)2·4H2O)络合,可以高选择性地得到绝对构型相反的共轭加成产物(ee值高达94%与93%).同样,使用同一金属前体Cu(OAc)2·H2O,与同一手性源出发合成的两种刚性不同的二胺配体络合,也可以在这个反应中实现产物绝对构型的反转(ee值高达94%与94%).     

Sensitive detection of a serum biomarker based on peptide nucleic acid-coupled dual cycling reactions

Serum level of disease markers may provide important guidance for diagnosis and prognosis. In this work, a sensitive and specific method suitable for direct serum detection of biomarkers is developed based on peptide nucleic acid (PNA)-coupled DNA cycling reactions with dual amplification. In this method, PNA released from a target-triggered homogeneous DNA cycling is employed to initiate an interface DNA cycling, and both of the cycling reactions are based on polymerase-assisted strand displacement reaction. Consequently, two PNA-coupled DNA cycling steps can take place simultaneously in one-pot, leading to greatly enhanced limit of detection and simplified operation. This method has also been successfully applied for evaluating serum insulin in pregnant women as an indicator of gestational diabetes mellitus. So the application of this method in real bio-samples may allow it to hold considerable potential in clinical practice. In addition, since there is no requirement for specific sequence of aptamer, the strategy proposed can be extended for the detection of many other protein markers and peptide-hormones in the future.