Symmetry-Protected Quantum Adiabatic Evolution in Spontaneous Symmetry-Breaking Transitions

Quantum adiabatic evolution describes the dynamical evolution of a slowly driven Hamiltonian. In most systems undergoing spontaneous symmetry-breaking transitions, the symmetry-protected quantum adiabatic evolution can still appear, even when the two lowest eigenstates become degenerate. Here, a general derivation to revisit the symmetry-dependent transition and the symmetry-dependent adiabatic condition (SDAC) is given. Further, based on the SDAC, an adiabatic-parameter-fixed sweeping scheme is used for achieving fast adiabatic evolution, which is more efficient than the linear sweeping scheme. In the limit of small adiabatic parameter, an analytic inequality is obtained for the ground state fidelity only dependent on the adiabatic parameter. The general statements are then demonstrated via two typical systems. Besides, the robustness of the symmetry-dependent adiabatic evolution against weak symmetry-breaking sources is studied. The findings can be tested via the techniques in quantum annealing and may provide promising applications in practical quantum technologies.     

Enhancing the Peroxygenase Activity of a Cofactor-Independent Peroxyzyme by Directed Evolution Enabling Gram-Scale Epoxide Synthesis

Peroxygenases selectively incorporate oxygen into organic molecules making use of the environmentally friendly oxidant H₂O₂ with water being the sole by-product. These biocatalysts can provide ‘green’ routes for the synthesis of enantioenriched epoxides, which are fundamental intermediates in the production of pharmaceuticals. The peroxyzyme 4-oxalocrotonate tautomerase (4-OT), catalysing the epoxidation of a variety of α,β-unsaturated aldehydes with H₂O₂, is outstanding because of its independence from any cost-intensive cofactor. However, its low-level peroxygenase activity and the decrease in the enantiomeric excess of the corresponding α,β-epoxy-aldehydes under preparative-scale conditions is limiting the potential of 4-OT. Herein we report the directed evolution of a tandem-fused 4-OT variant, which showed an ∼150-fold enhanced peroxygenase activity compared to 4-OT wild type, enabling the synthesis of α,β-epoxy-aldehydes in milligram- and gram-scale with high enantiopurity (up to 98 % ee) and excellent conversions. This engineered cofactor-independent peroxyzyme can provide new opportunities for the eco-friendly and practical synthesis of enantioenriched epoxides at large scale.     

High Performance Bifunctional Electrocatalysts Designed Based on Transition-Metal Sulfides for Rechargeable Zn–Air Batteries

Due to the energy crisis by the excessive consumption of fossil fuels, Zinc–air batteries (ZABs) with high theoretical energy density have attracted people‘s attention. The overall performance of ZABs is largely determined by the air cathode catalyst. Therefore, it is necessary to develop high-efficiency and low-cost bifunctional catalysts to replace noble metal catalysts to promote the development of ZABs. Among a variety of cathode catalysts, TMS has become a research hotspot in recent years because of its better electrical conductivity than metal phosphides and metal oxides. In this work, we focus on the means of improving the electrocatalytic performance of transition-metal sulfides (TMS) providing ideas for us to rationally design high-performance catalysts. Furthermore, the performance improvement law between catalyst performance and ZABs is also discussed in this work. Finally, some challenges and opportunities faced in the research of TMS electrocatalysis are briefly proposed, and strategies for improving the performance of ZABs are prospected.     

箱型结构损伤分析的空间网格多尺度模拟方法

为高效模拟空间效应显著的结构在关键局部的损伤，本文研究建立了以损伤分析为目标的空间网格多尺度模拟方法．首先基于变形协调法和内力平衡法，研究了空间网格多尺度建模中的跨尺度界面连接方法，对比分析了两种界面连接合理性．以三跨连续刚构混凝土箱梁在地震载荷下的损伤为分析案例，验证了空间网格多尺度模型在结构损伤分析中的可行性及其在计算效率上的优越性．分析结果表明：空间网格多尺度模型可以精确模拟结构的静力效应和动力特性；空间网格多尺度模型既考虑了结构空间效应，又可以高效分析箱梁结构局部易损部位的损伤演化过程，从而为空间效应显著的结构损伤分析提供了更为实用精细的计算模拟方法．     

Electrocatalytic hydrogen evolution of conducting coordination polymers based on 1,1,2,2-ethenetetrathiolate

Electrocatalysis based on metal–organic coordination polymers (CPs) catalyst, especially metal-1,1,2,2-ethenetetrathiolate (ett), has received increasing attention due to their high-electrical conductivity, unique morphology and excellent redox activity. Here, amorphous powder of CPs is synthesized and firmly coated on the surfaces of carbon fiber cloth (CFC), then serves as active electrocatalyst for hydrogen evolution reaction (HER). The operating overpotentials of the poly[K_x(M-ett)] (Co, Ni or Cu) are 0.43, 0.36, 0.45 V, respectively, at a current density of 10 mA cm⁻² with pH = 0, along with the Tafel plot of 144, 153, 329 mV dec⁻¹. Moreover, they show remarkable electrolysis stability under harsh acid conditions. This study extends the HER application of poly[K_x(M-ett)] coating on CFC surfaces.     

Rational Construction of a N,F Co-doped Mesoporous Cobalt Phosphate with Rich-Oxygen Vacancies for Oxygen Evolution Reaction and Supercapacitors

Transition-metal phosphates have been widely applied as promising candidates for electrochemical energy storage and conversion. In this study, we report a simple method to prepare a N, F co-doped mesoporous cobalt phosphate with rich-oxygen vacancies by in-situ pyrolysis of a Co-phosphate precursor with NH₄⁺ cations and F⁻ anions. Due to this heteroatom doping, it could achieve a current density of 10 mA/cm² at lower overpotential of 276 mV and smaller Tafel slope of 57.11 mV dec⁻¹ on glassy carbon. Moreover, it could keep 92 % of initial current density for 35 h, indicating it has an excellent stability and durability. Furthermore, the optimal material applied in supercapacitor displays specific capacitance of 206.3 F g⁻¹ at 1 A ⋅ g⁻¹ and maintains cycling stability with 80 % after 3000 cycles. The excellent electrochemical properties should be attributed to N, F co-doping into this Co-based phosphate, which effectively modulates its electronic structure. In addition, its amorphous structure provides more active sites; moreover, its mesoporous structure should be beneficial to mass transfer and electrolyte diffusion.     

Resources and Methods for Engineering “Designer” Glycan-Binding Proteins

This review provides information on available methods for engineering glycan-binding proteins (GBP). Glycans are involved in a variety of physiological functions and are found in all domains of life and viruses. Due to their wide range of functions, GBPs have been developed with diagnostic, therapeutic, and biotechnological applications. The development of GBPs has traditionally been hindered by a lack of available glycan targets and sensitive and selective protein scaffolds; however, recent advances in glycobiology have largely overcome these challenges. Here we provide information on how to approach the design of novel “designer” GBPs, starting from the protein scaffold to the mutagenesis methods, selection, and characterization of the GBPs.     

Oxygen vacancies and V co-doped Co_3O_4 prepared by ion implantation boosts oxygen evolution catalysis

Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER) performance of electrocatalysts. However, the synergistic interaction of the heteroatom and defect still needs further investigations. Herein, we demonstrated an oxygen vacancy-rich vanadium-doped Co_3O_4(V–O_v–Co_3O_4), fabricated by V-ion implantation, could be used for high-efficient OER catalysis. X-ray photoelectron spectra(XPS) and density functional theory(DFT) calculations show that the charge density of Co atom increased, and the reaction barrier of reaction pathway from O*to HOO*decreased. V–O_v–Co_3O_4 catalyst shows a low overpotential of 329 mV to maintain current density of 10 m A·cm~(-2), and a small Tafel slope of 74.5 m V·dec~(-1). This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.