摘要：Plant natural products are a kind of active substance widely used in pharmaceuticals and ***,the current production mode based on plant culture and extraction suffer complex processes and severe concerns for environmental and *** the increasing awareness of environmental sustainability,engineered microbial cell factories have been an alternative approach to produce natural *** engineering strategies have been utilized in microbial biosynthesis of complex phytochemicals such as dynamic control and substructure ***,Enzyme engineering including directed evolution and rational design has been implemented to improve enzyme catalysis efficiency and stability as well as change promiscuity to expand product *** this review,we discussed recent advances in microbial biosynthesis of complex phytochemicals from the following aspects,including pathway construction,strain engineering to boost the production.

摘要：To understand fundamental problems in hypersonic laminar-turbulent boundary layer transition for three-dimensional complex vehicles,a new standard model with typical lifting-body features has been proposed,named as hypersonic transition research vehicle(HyTRV).The configuration of HyTRV is fully analytical,and details of the design process are discussed in this *** transition characteristics for HyTRV are investigated using three combined methods,i.e.,theoretical analyses,numerical simulations,and wind tunnel *** show that the fully analytic parameterization design of HyTRV can satisfy the model simplification requirements from both numerical simulations and wind tunnel ***,the flow field of HyTRV reveals typical transition mechanisms in six relatively separated regions,including the streamwise vortex instability,crossflow instability,secondary instability,and attachment-line ***,the proposed HyTRV model is valuable for fundamental researches in hypersonic boundary layer transition.

摘要：With the fast development of nanotechnology,reactive engineered nanomaterials(ENMs)are increasingly discharged into the environment,where they interact with environmental components and organisms and thus pose potential *** interactions-derived formation of nano-environmental and nano-bio interfaces determines environmental behaviors and biological effects of ENMs,and ubiquitous dissolved organic matter(DOM)is bound to impact the interfacial interactions and the resulted environmental ***,we systematically investigated adsorptive interactions between ENMs and various DOM representatives,and thereby demonstrated the effects of DOM on the aqueous suspension/aggregation,mobility in porous media,adsorption of contaminants,transformation,and biological accumulation and toxicity of ***,we conclude that natural DOM can in general expand environmental distribution of ENMs while limit their toxicity to organisms.

摘要：In this paper, a unified design procedure is given for output synchronization of heterogeneous multi-agent systems （MAS） on communication graph topologies, using relative output measurements from neighbors. Three different control protocols, namely, full-state feedback, static output-feedback, and dynamic output-feedback, are designed for output synchronization. It is seen that a unified design procedure for heterogeneous MAS can be given by formulation and solution of a suitable local L2-gain design problem. Sufficient conditions are developed in terms of stabilizing the local agents＇ dynamics, satisfying a certain small-gain criterion, and solving the output regulator equations. Local design procedures are presented for each agent to guarantee that these sufficient conditions are satisfied. The proposed control protocols require only one copy of the leader＇s dynamics in the compensator, regardless of the dimensions of the outputs. This results in lower-dimensional compensators for systems with high-order outputs, compared to the p-copy internal model approach. All three proposed control protocols are verified using numerical simulations.

摘要：Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped *** various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large *** the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight *** by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an *** propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston *** addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the *** mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah *** mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

摘要：Empirical research is playing a significant role in software engineering （SE）, and it has been applied to evaluate software artifacts and technologies. There have been a great number of empirical research articles published recently. There is also a large research community in empirical software engineering （ESE）. In this paper, we identify both the overall landscape and detailed implementations of ESE, and investigate frequently applied empirical methods, targeted research purposes, used data sources, and applied data processing approaches and tools in ESE. The aim is to identify new trends and obtain interesting observations of empirical software engineering across different sub-fields of software engineering. We conduct a mapping study on 538 selected articles from January 2013 to November 2017, with four research questions. We observe that the trend of applying empirical methods in software engineering is continuously increasing and the most commonly applied methods are experiment, case study and survey. Moreover, open source projects are the most frequently used data sources. We also observe that most of researchers have paid attention to the validity and the possibility to replicate their studies. These observations are carefully analyzed and presented as carefully designed diagrams. We also reveal shortcomings and demanded knowledge/strategies in ESE and propose recommendations for researchers.

摘要：The high incidence of cardiovascular disease has led to significant demand for synthetic vascular grafts in clinical ***-proliferation drugs are usually loaded into devices to achieve desirable anti-thrombosis effects after ***,the non-selectiveness of these conventional drugs can lead to the failure of blood vessel reconstruction,leading to potential complications in the long *** address this issue,an asymmetric membrane was constructed through electro-spinning *** bilayer membrane loaded and effectively released nitric oxide(NO),as hoped,from only one *** to the short diffusion distance of NO,it exerted negligible effects on the other side of the membrane,thus allowing selective regulation of different cells on both *** released NO boosted the growth of endothelial cells(ECs)over smooth muscle cells(SMCs)-while on the side where NO was absent,SMCs grew into *** overall structure resembled a native blood vessel,with confluent ECs as the inner layer and layers of SMCs to support *** addition,the membrane preserved the normal function of ECs,and at the same time did not exacerbate inflammatory *** preparing this material type that regulates cell behavior differentially,we describe a new method for its application in the cardiovascular field such as for artificial blood vessels.

摘要：In the context of global climate change and urbanization,urban flooding is an important type of natural disaster that affects urban development,especially in china,which is experiencing rapid *** the past 10 years,urban flooding events have caused huge disaster losses in Chinese *** has resulted in significant negative effects on the urban infrastructure,socioeconomic systems,and urban residents,thus causing widespread *** have confirmed the change in extreme rainstorms is due to the changing environments in many cities *** studies on the impact of these rainstorms with different characteristics for urban flooding is valuable for coping with unfavorable *** addition,numerical simulations provide an economical and viable means to perform these *** paper presents a numerical model of Xiamen Island in *** were conducted for 12 design rainstorm events with different return periods,rain patterns,and *** results indicate that,in the case of an equal rainfall amount,the rainfall intensity is the key factor that affects the inundated area,depth,and ***,the rainfall intensity is not the only determining factor;the rainfall pattern also affects the *** regard to the rainfall pattern,a higher rainfall peak coefficient usually leads to severe urban inundation and *** a result,the lag time would be shorter,which may further exacerbate the impact of urban flood *** results of this study provide insights into managing flood risks,developing urban flood prevention strategies,and designing flood prevention measures.

摘要：The organized alignment of cells in various tissues plays a significant role in the maintenance of specific *** induce such an alignment,ideal scaffolds should simulate the characteristics and morphologies of natural *** structures that guide cell orientation are used to facilitate tissue regeneration and *** here review how various aligned structures are fabricated,including aligned electrospun nanofibers,aligned porous or channeled structures,micropatterns and combinations thereof,and their application in nerve,skeletal muscle,tendon,and tubular dentin *** future use of aligned structures in tissue engineering is also discussed.

摘要：The rational design and construction of hierarchically porous nanostructure for oxygen reduction reaction (ORR) electrocatalysts is crucial to facilitate the exposure of accessible active sites and promote the mass/electron transfer under the gas-solid-liquid triple-phase condition. Herein, an ingenious method through the pyrolysis of creative polyvinylimidazole coordination with Zn/Fe salt precursors is developed to fabricate hierarchically porous Fe-N-doped carbon framework as efficient ORR electrocatalyst. The volatilization of Zn species combined with the nanoscale Kirkendall effect of Fe dopants during the pyrolysis build the hierarchical micro-, meso-, and macroporous nanostructure with a high specific surface area (1,586 m^(2)·g^(−1)), which provide sufficient exposed active sites and multiscale mass/charge transport channels. The optimized electrocatalyst exhibits superior ORR activity and robust stability in both alkaline and acidic electrolytes. The Zn-air battery fabricated by such attractive electrocatalyst as air cathode displays a higher peak power density than that of Pt/C-based Zn-air battery, suggesting the great potential of this electrocatalyst for Zn-air batteries.