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Marine urease with higher thermostability, pH and salinity tolerance from marine sponge-derived Penicillium steckii S4-4

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Marine Life Science & Technology 2021年第1期3卷 77-84页

作者： Changrong Liu Yao Xiao Yilin xiao Zhiyong Li Marine Biotechnology Laboratory State Key Laboratory of Microbial MetabolismSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghai 200240China

Urease has a broad range of applications,however,the current studies on urease mainly focus on terrestrial plants or microbes.Thus,it is quite necessary to determine if marine-derived ureases have diferent characteristics from terrestrial origins since the fnding of ureases with superior performance is of industrial interest.In this study,the marine urease produced by Penicillium steckii S4-4 derived from marine sponge Siphonochalina sp.was investigated.This marine urease exhibited a maximum specifc activity of 1542.2 U mg protein−1.The molecular weight of the enzyme was 183 kDa and a single subunit of 47 kDa was detected,indicating that it was a tetramer.The N-terminal amino acid sequence of the urease was arranged as GPVLKKTKAAAV with greatest similarity to that from marine algae Ectocarpus siliculosus.This urease exhibited a K_(m) of 7.3 mmol L^(−1) and a V_(max) of 1.8 mmol urea min^(−1) mg protein^(−1).The optimum temperature,pH and salinity are 55℃,8.5 and 10%,respectively.This urease was stable and more than 80%of its maximum specifc activity was detected after incubating at 25–60℃for 30 min,pH 5.5–10.0 or 0–25%salinity for 6 h.Compared with the terrestrial urease from Jack bean,this marine urease shows higher thermostability,alkaline preference and salinity tolerance,which extends the potential application felds of urease to a great extent.

关键词： Marine urease Penicillium steckii Thermostability Alkali resistance Salinity tolerance

Giant tortuous umbilical vein in a cirrhotic patient

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Hepatobiliary Surgery and Nutrition 2021年第3期10卷 428-429页

作者： Yao Xiao Shunda Du Department of Liver Surgery Peking Union Medical College HospitalBeijingChina

HepatoBiliary Surgery and Nutrition,Vol 10,No 3 June 2021A 59-year-old male was admitted to our department with abdominal distension,splenomegaly and liver cirrhosis.MRI showed a Segment-6 tumor(Panel A)and a giant dilated vein(Panel A and B).During the laparoscopic hepatectomy,a tortuous umbilical vein was found(Panel C).The patient had no complications or recurrence in an 8-month follow-up.

关键词： admitted Surgery patient

Polynomial Entropy of Amenable Group Actions for Noncompact Sets

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Acta Mathematica Sinica,English Series 2023年第7期39卷 1351-1368页

作者： Lei LIU xiao yao ZHOU School of Mathematics and Statistics Shangqiu Normal UniversityShangqiu 476000China School of Mathematical Sciences and Institute of Mathematics Nanjing Normal UniversityNanjing 210023China

In this paper, we define and study polynomial entropy on an arbitrary subset and local measure theoretic polynomial entropy for any Borel probability measure on a compact metric space,and investigate the relation between local measure-theoretic polynomial entropy of Borel probability measures and polynomial entropy on an arbitrary subset. Also, we establish a variational principle for polynomial entropy on compact subsets in the context of amenable group actions.

关键词： Bowen polynomial entropy local measure-theoretic polynomial entropy variational principle amenable group

Observation of the Hydrogen-Dislocation Interactions in a High-Manganese Steel after Hydrogen Adsorption and Desorption

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1105-1112页

作者： Dayong An Yuhao Zhou Yao Xiao Xinxi Liu Xifeng Li Jun Chen Department of Plasticity Technology School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200030China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China

Hydrogen embrittlement(HE)poses a significant challenge for the development of high-strength metallic materials.However,explanations for the observed HE phenomena are still under debate.To shed light on this issue,here we investigated the hydrogen-defect interaction by comparing the dislocation structure evolution after hydrogen adsorption and desorption in a Fe-28Mn-0.3C(wt%)twinning-induced plasticity steel with an austenitic structure using in situ electron channeling contrast imaging.The results indicate that hydrogen can strongly affect dislocation activities.In detail,hydrogen can promote the formation of stacking faults with a long dissociation distance.Besides,dislocation movements are frequently observed during hydrogen desorption.The required resolved shear stress is considered to be the residual stresses rendered by hydrogen segregation.Furthermore,the microstructural heterogeneity could lead to the discrepancy of dislocation activities even within the same materials.

关键词： Hydrogen embrittlement Stacking fault Dislocation movement High-manganese steel Electron channeling contrast imaging(ECCI)

Humidity sensor based on BiOBr synthesized under ambient condition

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Journal of Semiconductors 2022年第12期43卷 95-100页

作者： Chaofan Cao Guixian xiao yao Lu Second Affiliated Hospital Shenyang Medical CollegeShenyang 110035China State Key Laboratory of Automotive Safety and Energy School of Vehicle and MobilityTsinghua UniversityBeijing 100084China

Flexible humidity sensors are effective portable devices for human respiratory monitoring.However,the current pre-paration of sensitive materials need harsh terms and the small production output limits their practicability.Here,we report a syn-thesis method of single-crystal BiOBr nanosheets under room temperature and atmospheric pressure based on a sonochemic-al strategy.A flexible humidity sensor enabled by BiOBr nanosheets deliver efficient sensing performance,a high humidity sensit-ivity(Ig/I0=550%)with relative humidity from 40%to 100%,an excellent selectivity,and a detection response/recovery time of 11 and 6 s,respectively.The flexible humidity sensor shows a potential application value as a wearable monitoring device for res-piratory disease prevention and health monitoring.

关键词： human breathing BiOBr nanosheets sonochemical strategy flexible humidity sensor

Difference Independence of the Euler Gamma Function

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Chinese Annals of Mathematics,Series B 2023年第4期44卷 481-488页

作者： Qiongyan WANG xiao yao School of Mathematical Sciences Peking UniversityBeijing 100871China School of Mathematical Sciences Nankai UniversityTianjin 300071China

In this paper,the authors established a sharp version of the difference analogue of the celebrated Holder’s theorem concerning the differential independence of the Euler gamma functionГ.More precisely,if P is a polynomial of n+1 variables in C[X,Y0,…,Yn-1]such that P(s,Г(s+a0),…,Г(s+an-1))≡0 for some(a0,…,an-1)∈Cn and ai-aj■Z for any 0≤i

关键词： Algebraic difference independence Euler gamma function Algebraic difference equations

Hexagonal packing lattice formed by functionalized gold nanoparticles

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Rare Metals 2022年第11期41卷 3858-3864页

作者： xiao-Bin Mang Lian-Qi yao Department of Research and Development Shanghai YS Information Technology Co.LtdShanghai200240China Department of Quality Inspection Shanghai Hutchison PharmaceuticalsShanghai200331China

Nanostructures formed by functionalized gold nanoparticles(GNPs)were studied using X-ray diffraction(XRD).Two systems of such functionalized GNPs,one with gold core grafted by both ligand(rod-like liquid crystalline molecule)and co-ligand(alkylthiols)and the other one with only ligand grafted,were studied.The presence of ligands and co-ligands increases the mobility of GNPs and induces long-range ordered packing style with the change of temperature.In both systems,functionalized GNPs form columns first and then pack on hexagonal lattice.It is found that the correlation along column direction is dependent on surface conditions of GNPs,which is observed for system with only ligand grafted.Based on experimental results,size of gold core and number of ligand and co-ligand belonging to each gold core were calculated.Diffraction intensities and electron density map of each structure were simulated,which are evidently similar to experimental ones.Finally,structure model was proposed and discussed.The results help us to understand and control the way that organic molecules affect the organization of nanoparticles,and facilitate the design of new hybrid materials.

关键词： Nanostructures Gold nanoparticles Simulation

Grazing-incidence small-angle X-ray scattering property of double-layered gold nanoparticle arrays

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Rare Metals 2022年第10期41卷 3585-3590页

作者： xiao-Bin Mang Lian-Qi yao Department of Research and Development Shanghai YS Information Technology Co.LtdShanghai200240China Department of Quality Inspection Shanhai Hutchison PharmaceuticalsShanghai200331China

Gold nanoparticle arrays fabricated via layerby-layer technique were investigated using grazing-incidence small-angle X-ray scattering(GISAXS) method.Samples containing two gold nanoparticle layers that were separated by 5,11,15 and 21 poly electrolyte(PE) interlayers were studied.By using different X-ray incident angles,correlations of gold nanoparticles(GNPs) in the same layer and in two different layers were investigated.It is found that both sideway correlations between GNPs in the same layer and vertical correlation between two gold nanoparticle layers depend on the thickness of PE interlayers.According to sideway correlation,the size of GNPs is determined to be(13.0±0.5) nm in all of the four samples,which was also proved by scanning electron microscopy(SEM) and theoretical calculation of form factor of spherical particles.From vertical correlation,distance between two gold nanoparticle layers was determined for sample with 11,15 and 21 PE layers.These distances can be reasonably explained with the number of PE layers and the thickness of single PE layer.These results indicate that by repeated depositing of oppositely charged PE layers,a true three-dimensional(3 D) nanostructure can eventually be designed.

关键词： Gold nanoparticle array 3D nanostructure Grazing-incidence small-angle X-ray scattering Form factor Nanocomposites

Robust autonomous landing of UAVs in non-cooperative environments based on comprehensive terrain understanding

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Science China(Information Sciences) 2022年第11期65卷 163-177页

作者： Lyujie CHEN Yao Xiao Xiaming YUAN Yiding ZHANG Jihong ZHU Department of Computer Science and Technology Tsinghua University Department of Precision Instrument Tsinghua University Department of Automation Tsinghua University

Autonomous landing in non-cooperative environments is a key step toward full autonomy of unmanned aerial vehicles(UAVs). Existing studies have addressed this problem by finding a flat area of the ground as the landing place. However, all these methods have poor generalization ability and ignore the semantic feature of the terrain. In this paper, we propose a well-designed binocular-LiDAR sensor system and a robust terrain understanding model to overcome these deficiencies. Our model infers both morphologic and semantic features of the ground by simultaneously performing depth completion and semantic segmentation. Moreover, during the inference phase, it self-evaluates the accuracy of the predicted depth map and dynamically selects the LiDAR accumulation time to ensure accurate depth prediction, which greatly improves the robustness of the UAV in completely unknown environments. Through extensive experiments on our collected low-altitude aerial image dataset and real UAVs, we verified that our model effectively learned two tasks simultaneously and achieved better performance than existing depth estimation-based landing methods. Furthermore, the UAV can robustly select a safe landing site in several complex environments with about 98% accuracy.

关键词： UAV autonomous landing terrain understanding depth completion semantic segmentation